Maybe you could add more formable nations? Like both for the old and new world? Perhaps some new world nations being based on culture? like if it's a Scandinavia culture They can form Vinland instead of Canada? Oh! and Maybe US States can be formable and/or releasable/revolter states?

Does this count as flavor or gameplay suggestions?

so, I like the idea of more flavour in the new world, but I guess that project already exists.
I've been using the 'New World Colony Names' mod by Cwrwi that pretty much does that and it's compatible with this mod as well ;)

For Great Britain, the Irish Revolution lends itself pretty well to the game's mechanics, particularly as a disaster; while in terms of military involvement it was a guerilla war involving only about 50-60,000 men between both sides, it was a massive hit to Great Britain and Ireland with various affects across the board, and while not affecting many provinces it is certainly a stark change to the late-game map.

Could start off with an event in 1916 to represent the Rising in Dublin with maybe a stability hit/very small rebellion spawning in Leinster.

Decisions could be put in place to allow simulation of the two possible approaches; crushing the rebellion or conceding to the demands (IRL history being the former choice taken) and an ensuing period of Revolutionary rebellions, with the end result either being an independent Ireland or an Ireland as a March etc

Would be very happy to provide any of the writing/information in regards to the event, just not so clued in on the modding aspect! I just think very late-game disasters are interesting since they hit moreso the nation itself rather than having a drawn out military impact.

Maybe there could be a event or decision to allow Austria to form Germany if 1. Their a great power, 2. The HRE no longer exists and 3, they have some sort of control over German minor states and good relations with Prussia(If Prussia exists) and/or a major german power? At the very lest allow them to vassalize German minor states? I'm not entirely sure how it would work but it was a possibility IRL, but Austria didn't want to do it because that would mean giving up their non-german lands, Which the event or decision would probably do.

The U.S. civil war would be nice. Where the player has to decide whether to keep slavery or not, or whether to let the south keep slavery or not rather, and that in turn leads to the war if not or high unrest if so; maybe occuring if one puts off passing a social reform for slavery too long?? Idk. Also, maybe adding events such as the boxer rebellion and the opium wars to show the battle for supremacy between china and the west would be pretty cool as well. Lastly, and this is the big one, a WW1 start date and mission/event tree would be exquisite! Maybe tying in the volatility of the Balkans and if unrest gets too high in the Austro-Hungarian Empire (specifically the bosnian provinces) or their relationship with Serbia is bad enough then the assassination of Ferdinand occurs. Your addition of trenches gives me hope that my dream of simulating WW1 in EU4 will come true lol. Great work so far!

1. 'US Civil war' shown through disaster and 1861 scenario
2. 'Belgian Kongo' event
3. Event for GBR about break up of royal union with Hannover and 1836 scenario
4. Some flavour in Thirteen Colonies to make the 1776 war. And of cource to add possibilities to avoid it.
5. Some events or decisions in Japan to show the westernisation of Japan and gaining military and industrial power.
6. And events/decisions to show the decline of China. Taiping war, christian preachers in South China etc.

And of course, 1914, 1848, 1917/1918, 1922, 1870/1871 scenarios.

Italian unification idea:
Starting in 1841-1848 (mtth event) all Italian states get major event "Young Italy" giving all provinces in Italian region ITA cores. (represents growing popularity of Young Italy movement and Italian nationalism in general).

1859-1869 (mtth event of 120 months): "Garibaldi's Redshirts":
-All provinces
--Not owned by Great Power (GP) Italian nation
--with ITA core
---spawn ITA nationalist rebels (scaled to province owner's development)
GP Italian nation:
-event: "Italian Crown":
1. Accept crown (become ITA; any owned ITA lands integrated into GP first to keep capital/primary culture)
2. Reject 'gutter' crown (lose 25 prestige, ITA rebels spawn in all ITA core provinces)

Revolts should be scaled so that they are serious but not impossible to over come for large nations. This way the Papcy could potentially put down a revolt, but an Austrian Empire would need to focus on heavily on keeping northern Italy within its realm. Italian minors will most likely succum to unification.
If there are two Italian GPs, the one with more development will receive "Italian Crown" event, other will suffer rebels. An AI Italian GP would always accept decision
[If Sardinia-Piedmont exists, should be treated as GP if no Italian GP exists)

I apologize in advance if this is too involved. I hope this can help add some flavor to this awesome mod:)
As alwasy, feed back is welcome and deeply appreciated

Some ideas for descriptions for the events I mentioned in my previous post:

"Young Italy"
Founded in 1831 by Giuseppe Mazzini, the Young Italy movement looked to create an Italian Republic from the Austrian occupied Italian provinces. Mazzini believed that a united Italian republic could only be formed through popular insurrection, leading to a long career of pamphlet writing and insubordination. Despite being founded in exile, Mazzini's movement gained popular support throughout northern Italy, until revolts broke out in 1853 in favor of a democatic Italy.

Text: "Youth these days..."

"Garibaldi's Redshirts"
Despite failure in 1853 for unification, the desire for a unified Italy continued to persist. Hope resided in the appeal to a strong Italian state to lead unification. During the 1860s, a talented general, Guiseppe Garibaldi, lead a band of voluneers he recruited throughtout Italy to fight for unification. Under the blessing of Sardinia-Piedmont, Garibaldi lead an expedition to Sicily to overthrow the government and cede its territory to the leading Italian state.

Text: "He is no hero."

"Italian Crown"
The people of Italy have revolted against their oppressors. While they have made initial success, without a leader they will surely fail. We as the leading power in Italia are in a position to benefit from this. If we were to accept the people's offer of an "Italian crown", we could greatly augment our power in the region. However, if we refuse, our people will surely be enraged by our neglect of our Italian brothers and their struggle for freedom.

Text:
1. "Per la Gloria d'Italia" (For the glory of Italy)
2. "My station is beyond this, 'gutter crown.'"

For "Garibaldi", the text 'He is no hero' is for those Italian states who receive the event and are not a GP (in reference to his nickname, Hero of the Two Worlds). Rebels wouldn't be seen as liberating to those minor governments being replaced.

These event descriptions are simplified for EU4 purposes so to make creating these flavor events easier:) Those text in quotations are the "select" text

1. Canadian Independence in 1867 year. Is it possible to change status of colony to client state?
2. Some boosts to liberty desire of Spain`s colonies to show the fast downfall of Spanish colonial empire in 1815-1830 years.
3. Same boosts to liberty desire in Thirteen Colonies.

After WW1 there should be an event in anatolia to form Turkey either trough a decision or by rebellions. You should also be able to either join the rebels or fight against them as Ottomans or Rûm since its the Ottomans in blue

Warning Big Post
--Russia---
+You could also use a system similar to the protestent/catholic league's for the civil war so countries can back the 'White Russians' 'Red Russians'
+or perhaps use to condottier system as a expeditionary force mechanic may be more accurate as it could get messy with actual war declarations
-Russia should have missions to expand into machuria Korea and China (Gaizhou specifically) so Japan and Russia are forced together

----Qing/China event ideas-----
- Opium wars should represented through mission for England using mission tree
- French mission tree ideas to take south east asia
- Taiping rebellion should be a disaster
starts when :
-Not of chinese culture group
-Not chrisian
-stability is less that 1
(or something along those lines)
This would lead to a huge rebellion of multiple 50-100 k stacks to make it challenging.
- Boxer rebellion - not sure on this one perhaps should be an event for china with boxer rebellion on one side giving and instand war declaration with a boost to manpower + recovery and on the other economic de-buffs and loss in prestige, legitamact and mandate this would sort of shoe horn the player which could be annoying
+ This system could be simmilar to the idea stated above allowing expaditionary forces through the league system or condettier if possible for the European power + Japan
- If the war is lost there would be a spiral and mini Qing splosion with chinese republic being founded and warlords cliques breaking off
- WWI you could implement a event or decision to sacrifice man power for money 10,000 for 500-1,000 gold this could help fund the construction but make you vulnerable to japan and the west

----Japan events and missions-----
-when the USA colonises or invades the west coast they could have a decision
to send an expedition to japan
-this could result in Japan getting a Isolationism event to cause a war declaration and devistate musashi lowering devolpment by 10-15 or give the americans war reparations, +5 national unrest and put your isolation to open doors this would lead to.....
-the Boshin war which should be a disaster for Japan with the trigger conditions
-income - 1
-stability below 1
-Isolation = open doors
-unrest = +1
- this would result in large rebel stacks 50 - 80k
and a series of decisions to allow the rebel takover

- upon finishing the boshin war on the imperialist side the nation tag could become
'imperial Japan' (may be too long perhaps remain Japan)+ flag change to modern one
- the capital is moved to Musashi and be renamed Tokyo
- the government would become a constitutional monarch
- the nation would get a permanent buff called 'The Meiji Constitution' which would +5% institution spread ,- 10% development cost and +10% national manpower.(or similar)

-the mission tree would then be expanded to targeting Korea Machuria, Taiwan as well as pacific island micronesia and parts of china
-Korea could be a colonial region or be part of the dominion system you propose but renamed for flavour
+however could simply be a vassal as Korea retained its Royal dynasty for a time and then allow a diploannex
-mission to take Port Arthur so as to represent the russo-japanese war
-missions should also be construction focused with rewards being bonus development representing the westernisation
+ joining in on boxer rebellion etc and aquiring parts China not sure how to do international settlement but adding more provinces to china could be a possibility

—Republic of Ireland —
agreed with above post
this could be something along the lines of a” home rule”
event chain for the GB which would grant large amounts of autonomy to Irish provinces or it could be ignored. if it wet e ignored or a certain level of autonomy say 60% wasn’t reach in time the chain it would spark an Easter rising event creating rebel stacks and occupying the pale.
You could then have the Irish war of independence as a
disaster with the trigger conditions along the lines of
-autonomy below 60% in all Irish culture provinces
-less than 1 stability
-Easter rising event chain trigger ( if that’s even possible)
-Ireland does not exist

I'm playing a Multiplayer (Me as NL and my friend as Savoy) We are playing with Beyond Typus. Why the Crown of Italy never happens to my friend? He is the only GP in Italy and always one of the smaller Italian nations becomes Italy.

Maybe add some land clearing decisions to improve terrain types?