The listed Mongol religion should not be "Mongol (Pagan)", as in the case of the Ilkhanate, or Muslim, as in the case of the Golden Horde. It should be Tengriism - the Mongol khans derived their authority from the religion, you would think we could at least give it the right name.
The Golden Horde was not Muslim at this point in the game. Period. In fact, while the "khans of the Golden Horde" existed, they were still subjects of the Great Khan - a census by Mongke Khan was currently in process at the time the game starts! Still, the Ilkhanate and the Golden Horde should be separate for Mongol Civil War possibilities, I know, but in my opinion the Mongols in this game are massively underpowered. Horse archers are pretty impossible to utilize properly, even against infantry where they should be virtually unstoppable.
It's just silly to worry about the historical accuracy of the disc shield or whatever when we have glaring historical inaccuracies all over the campaign map. Jerusalem belonging to the KoJ is just one example. I frankly think that the Italian city-states were far more relevant in medieval history and far more worthy of faction slots than three random pagan tribes in the Baltics. Did those pagan tribes actually do anything other than get conquered in rapid succession by the Teutonic Order? Whereas the Italian states were involved in a long series of protracted, bloody wars. Don't even make them individual city states - make them a broader "league" state (call it the Holy League, even though it's totally out of place in this century, at least it's better than making them vassals of the HRE which they decidedly were not and should never have been in the first place), if you have to, though I really think the performance issues in the mod aren't stemming from the number of factions or the number of settlements because I've seen mods that perform better than this one - and have more factions!
To emphasize: it's stupid for there to be three separate Baltic tribes and then not a single Italian city state but Venice (a city far more defined by its machinations in the Med. than any sort of control it exerted over Northern Italy).
I don't like the Latin names for half the kingdoms in Europe and native names for the other half if someone on the mod team speaks the language. It's not that hard to look up - the Latin names are just arbitrary. Why does Bulgaria get a native-language name and Poland doesn't? Regnum Poloniae? It's "Królestwo Polskie" and I don't even speak the language - it was a five second Google search.