I recently installed a mod that removes the Cavalry 1.3x autocalculation bonus from the game, and started a new 1.3.0 playthrough, with no other mods that affect the balance of the game.
It is now something like day 250 275 or something like that and the game is the most balanced its ever been without using the mods "Revolutions" and "War Attrition". Neither Vlandians nor Khuzaits are snowballing the entire map. Khuzaits are doing the best (even without Cavalry 1.3x autocalculation bonus), having taken one town from Sturgia, one town from Northern Empire and one town from Aserai, and like one or two additional castles on top of that. Meanwhile, Western Empire/Battania/Vlandia are constantly duking it out, going back and forth.
Sturgia is finally capable of holding its own against the enemy factions in autocalculation, sometimes Sturgia wins sometimes they lose.
I think this observation ties back to two things: 1) The fact that the Cavalry 1.3x autocalculation bonus is very evidently giving Vlandia, Khuzaits and to a certain degree also Battania an unfair advantage which results in snowballing. 2) There's something else unique for the Khuzaits which makes them on average more powerful than the other factions.
I'd love to see other people try playing with this mod that removes Cavalry 1.3x autocalculation bonus and write down your own experience.