I will outline the changes I made to the original mod here as the workshop description page is limited.

Firstly the on_game_start_after_lobby effect has been correctly written so that it only fires the MBR on_action, which means there will be no duplicate vanilla on_actions firing at the start of a campaign.

I have changed the building creation so that it is hopefully more inline with the vanilla design. This means that the AI will fill all available holding building slots before upgrading other MBR buildings as per the vanilla design.

I have changed the build priority for the militia building to be more inline with the vanilla martial buildings hierarchy, so a castle should not build a Militia building, and cities/temples should place a higher emphasis on Regimental Grounds and Barracks over the Militia building.

Hopefully the AI will no longer spam Militia buildings.

I have also made various changes to existing buildings and added some love for tribal as the original mod didn't do much for them.

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CASTLE buildings
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Interior Expansion
Added light cavalry buffs at tier 4 because it was weird that only heavy cavalry benefit from the Inner Stables.
Added positive prisoner opinion at tier 6 as your new Dungeons are less drafty than the old ones, and there are rats to supplement their diets if they can catch them, and the view of the new gallows is inspiring.

Underground Work
Added hostile scheme resistance due to the various activities below ground and your ability to hide away from hostile schemes.
Added scheme secrecy at tier 3 because the secret passages provide much better means for moving about to spy on your guests, and also mess with their heads, or just outright assassinating them.

Town
Added county opinion at tier 3 because the new road system and town squares have impressed the local residents.
Added control at tier 3 because the new road system makes travel safer for the local residents and makes it easier for your patrols to move between the hamlets.
Added steppe terrain so towns can be built on the Steppe.

Support
Increased hostile raid time because those wooden logs are sturdy, stopping the raiders from just waltzing off with the local maidens and cattle.


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COMMON buildings
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Stables
Added horse archers at tier 2 because it seemed illogical that they were left out.
Added steppe & hills terrain because the Steppe is synonymous with horse domestication, breeding, and warfare.
Added Islam & Slavic religion because Muslim and Slav cultures used horses extensively, certainly as much as Europeans.

Hospital
Added stress buffs at tier 3 because there's nothing like a bowl of soup and husk of bread to relieve the day's burdens, and the relief from fencing off the unclean.

Militia
Changed province income nerf from negative income to a reduced province tax, which will hopefully stop the AI debt spiral associated with the building.
AI should no longer construct Militia buildings in castles.
AI is less likely to construct Militia buildings in temples.
Added steppe terrain because it made no sense Militia buildings could not be built on the Steppe.

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CITY buildings
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Trade District
Added retreat losses at tier 6 because of the new armour produced by the Tools & Weapons Smiths.

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TRIBAL buildings
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town square
Added monthly prestige gain to tier 3 due to the peacocking of all the lords to gather in front of all the local troops.

Simple Port
Added coastal advantage, and a disembarkation buff at tier 1
Added naval speed buff at tier 2

War Improvements
Added supply capacity buff at tier 2
Added supply duration buff at tier 3

Ting
Added new Ting building for local meetings to administer the tribe, elect the chief and mete out judgement for crimes.
Increases renown, monthly piety & prestige, and positive opinion from clergy, vassals, and dynasty.

Medicine Lodge
Added a building similar though not as elaborate as the Hospital. Tiers 1 to 5.
Provides increasing health benefits and vassal opinions as the tier level of the buildings rises.
Also provides increasing county development and growth as the tier level rises.