First off, great mechanics of this mod, I really like the set up!
However, I think vanilla Byz is OP and this mod will make them space marines.
So may I suggest a number of tweaks, not changing one bit of the mechanics so far, just tweaking your excellent set up?

Please allow me:

1. Bureaucracy Law 1, 2, 3 and 4.
An excellent system, however in my opinion tier 4 should be no negative modifiers and maybe no positive either. Perhaps a small bonus to MaA maintanance and maybe a 10+ opinion from vassals. This way the Byz is at optimal functioning, and can become a powerhouse when expanding.

But 3, 2 and 1 should however be a detoriating Byzantine state(Roman), as their coin gets debased the upkeep of the armies gets harder to maintain, the weakness of the realm is ever more noticable to other independent rulers, public opinion is not at its best and vassals gets less and less loyal(opinion) as they seek new leadership in the semi republican Roman state.
So when at 1, its an uphill battle to restore the state, end the civil wars and make the legal codes renewed or restored to a respectful place among the Romans, creating stability.

In other words, this slider of laws could be how respected Roman laws is, or what state it is in. 1 = the laws have detoriated, few respect them anymore and corruption is rampant. The Roman state is in turmoil.
While 4 = Roman peace and order is restored, laws have been reinvigored, the state is functioning and its subjects are happy and loyal, well, as loyal as can be.. stay vigilant.

Some further ideas is to add scheming resistance into the fold, making schemes more likely to succeed when at 1 for example.
Vassal opinion at 1 should be harsher in my opinion, and then gradualy reach 0 at Law 4.
Since laws are losing its authority, both vassals and counties of different faith or culture is increasingly targeted or blamed for the ills of the empire, making them less happy, while at law 4 maybe a tiny bonus if any.

So thats my thoughts for number 1.
Ill post a new post per suggestion.

2. Vassal limit and Laws.

Smaller thought, as the government gives a +20 vassal limnit but law 1 gives -30, which in reality only lands on a -10 in total. With everything calculated the vassal limit lands on 85, not counting artifacts making -10 unnoticable.

I suggest removing the +20 for being imperial, and decreasing the vassal limit when at law 1 with lets say -50.
This would land the total at 45, not counting artifacts, and to compare that the starting vassal count in 1066, is 32 vassals, which is at 1066 the largest extent the Byzantine Empire(Roman) was after the rise of Islam, due to Basil IIs reign.
If you start counting kingdom tier vassals you only need about 30 to reach classical Roman EMpire borders(England to Egypt), so this law system tied with vassal limit could start giving a strong impact on the empire if it is getting big but have a lot of small vassals. This way they have to consolidate power into fewer hands, which again prove dangerous.

3. Salaries & Roman Contracts

Love the system, however it is increadibly lenient in my opinion.
First of the the low salary is at an incredible 38,5% taxes, way stronger than feudals, so it is both a low salary in Roman eyes, giving a -5 opinion which is easy to ignore, and a huge tax income compared to standard feudal at I think 25%?

Let me suggest that all taxes, and levies be reduced a lot.

lets say:
No salary=40% tax, -50 opinion
Low salary=30% tax, -30 opinion
normal salary=20% tax, -10 opinion(Because normal is okey, but never quite enough)
High salary=12% tax, +10 opinion
Very High Salary=7% tax, +15 opinion
Pronoia=0%, +20 opinion.

For the contracts, like Theme I would decrease levies accross the board.
40% levies is super OP, combined with those super taxes above this government can steamroll pretty fast. lots of levies, lots of cash, lots of MaA.

I am not sure about all of them but I would make levy contribution standard(Theme) as low as 15%. This combined with the Theme vassal himself getting a +10% tax income due to people who pay a tax to skip service. This will indirectly impact income from vassals again, but at Pronoia will serve as a +10% tax bonus for keeping all those extra skip military service taxes for themselves.

As for Exarchate, it as it stands now is just 100% better than Theme, and even more OP.
In reality the Exarchates, which existed before and under the rise of Islam, when the Eastern Roman Empire still had its possesions in the Levant, Egypt and Nort Africa, was a troublesome lot.
the Exarchates was the new Provincial governors, but had quite a lot political and military power so that many Emperors had to tread carefully.
They could sometimes also show semi independence like the Exarchate of Carthage(Encompassing North Africa to the west of Egypt), which refused to send soldiers and money to Constantinople both due to relations with the emperor and because of real concern from local threats to their immidiate area.

So I suggest Exarchate should make for a somewhat pleased vassal, which gives you the benefit of avoiding too many vassals etc, but should give less levies, and the Exarch should maybe have some personal buffs to their ability to raise MaA, in order to both be effective Military sectors, but also give a double dged sword, they might become more dangerous in factions too.
taxes could stay normal, or have a slight reduction, due to big b
government issues, like a big bureaucracy, distances, many layers of government or other arguments.

But the clue is to make the government a more dynamic and challanging playthrough.

4. Turks, Nomads, Arabs, Normans and later the Latin west.

This will be a different type of suggestion/wish.
If you can, it would be awesome for events that makes the Byzantine playthough invlve the constant threats it historically had, with Nomads north of the Danube, annual Arab jihads and raids in Anatolia, the Turk Nomads raiding and expanding into Anatolia, the Normans eying weakness from southern Italy and later the Catholic world turning sour on the Romans.

I sorely miss having to pay of nomads, and staying vigilant in the east, which histirically never ceased to give the Byzantine Romans much of a pause.
This is also why it was hard to expand, as if they gathered their army in the east the western neighbours noticed it, like the Bulgars, Avars, Pechenegs etc, and if the Romans turned to the western halv, fighting the Bulgars for example, they always feared their eastern borders, hence they had toeither gamble or use amuch smaller force in the west to fight the Bulgars(Which they saw as a lesser threat than their eastern enemies.

Btw: I noticed now that your government gives a -50% levies, as it is Roman Imperial Government, this comes atop the -25% because of Roman Legacy tradition.
This is one way of reducing levies of course, but I think I rather keep the limits within the contracts, making it possible to get a decently large imperial army if your really really good, and most of the time struggling to maintain the balance of internal peace vs salaries and levies etc..

Food for thought. Anyway, you can always use that modfier of yours to balance out the army size that way, it is simple, but it works!

Oh one cool suggestion!

Add a legitimacy system, icon could be bext to dread, gold etc, showing 0-100 legitimacy.
Firstly, battles and war outcomes move this up and down. Losing too many battles will lower the scale too much and vassals want to seek out a new Emperor more competant to lead the Romans.
But being born in the purple, have had the throne for many years and being a brilliant strategist might give you some extra bonus to the legitimacy scale, making you take som extra hits too it.

So 100 is of course no doubt about your legitimacy, 0 sparks a coup(maybe by event?)
and the closer you get to 0 the more likely vassals might join a faction to install a more competent ruler.

Also, a bonus idea on this, maybe scheming might be more prevalent on low legitimacy, or their success chance increase a little, the closer you get to 0?

And 0, the event was just a thought, it could be solved differently too, but if no faction has formed or triggered yet this could be a way to stop the faction way of handling this and spawn a promising commander of one of the vassal dynasties, which then makes vassals choose between you or him.

Perhaps the contract system can be linked to a heritage.

Byzantine Traditions gets theme, ect

Roman Traditions gets Praeses, Ect.

Originally posted by nsinger998:

Perhaps the contract system can be linked to a heritage.

Byzantine Traditions gets theme, ect

Roman Traditions gets Praeses, Ect.

well its practically the same thing from all the research ive done.

praeses is just theme but latin(not exactly) but its essentially saying the same thing. governor

I know, But the system as is is limited. By tying which one you get to a heritage; You will be able to extend the system to hybrid cultures(Romano Gallic, Ect).

If possible maybe an event when a vassal dies to seize their title or give it to their heir to simulate the provincial governors. Only possible with a certain bureaucratic law, with benefits and consequences with either choice of course.

I think I meant traditions, My mistake.

Well its the central governmetn who decides the title names,and if they are Greek speaking it will be Greek names to the titles, regardless if the vassal is Greek, Italian or Portuguese.
If the central government changes the official language(I would say court language in CK3)
then the titles would change.

What would be cool, but probably not possible, is to have two official languages.
Greek and Latin for a restored Empire.

The main issue with Imperial government in real life was simple logistics much of the time. There was a reason that system worked better along the Mediterranean. It allowed quick trade and administration in Italy, Greece, Spain, and much of North Africa along with Near East. The issue is having to fight wars or raids/incursions on multiples fronts with a centralized military vs regional feudalism system military along frontier especially inland or areas not easily accessible by sea. That one reason east and west empire split. They became empire when republic was demean impractical for the size of it. Then split between two emperors when they demean that even too much for one strongman to manage.

The Greeks were always more autocratic leaning vs more Republican traditions of the Italians. This is seen with Venice and later republics in Italy. Even noble families in Italy are more Plutocratic by this point and take from Patrician traditions.
The Germanic invasions of Western Europe and later northern and eastern Europe laid the foundation for feudalism system they spearheaded. The pope and church in West would often use Germanic barbarians later lords as their jackboot enforcers.

I saw you want to add a Western Roman Empire too? Can I recommend special government for that and based around Holy Roman Empire(they can adopt government too)? Any Christian or maybe even any pagan in former Western Rome who is feudalized that meet requirements can reform western empire?
Although the government is more of a decentralized confederation or "empire" like the Holy Roman one or even like Shogunate Japan where Emperor is symbolic and figurehead largely.
This is contrast with East where emperor is top man. In West emperor might become puppet of the pope or newly reform senate. The senate in the west being more aristocratic and hereditary along with having more power. The senate has been feudalized in west which means they are all appointed members from prominent or local noble families(works in game too). This being the second or third sons of kings and dukes who are sent to Rome to represent their family/titles as senators. Governors now are largely theocratic in position/appointment. They are knighted members of a Holy Order or a local Cardinal and appointed as the regional military wing of the church at the local level if you reform west as Christian with Catholic rites or similar ones.

Also, decision for Greeks to "re-embrace Hellenistic legacy"(not religion. The Greek Culture) which basically renounces their claim to legacy of Rome and focus more on legacy of Alexander, Hellenistic Empires afterwards, and Eastern Christianity legacy. Which would make sense if not on terrible terms with West and more concern about Islam/caliphates or Khanates and Persia while not being able to act against West. Think of it like Danelaw decision and how they basically draw line between England and Danelaw.
The Western Empire in such a case would change it name to to Just Roman Empire but lose claims to east. Also, they can take decision forcing Byzantium to accept such terms likely by way of war. The pope is likely like a shogun in power and influence within a Christian Western Rome.