I finished today a test run with 40+ years (without player interaction) and with the recent changes the Khuzaits are not dominating the world anymore. It seems the recent updates and rebellion helped to some extent.I like to add some suggestions to my previous post:
i feel that the consensus of OP ness of the Khuzait comes from their cultural speed bonus + extra speed bonus based on having more cavalry and the bonus to cavalry in autocalc simulations.
They can recruit quicker, avoid bad confrontations and form armies quicker.
Instead of nerving their speed or adding more cavalry to the other factions. Seek a solution in other area's. Their speed and army build makes them unique. The major problem is that the khuzait are generally taking over large portions of the map, so every battle in the endgame is against horse archers.
options (not all in once ):
-Reduce the amounts of khuzait recruits
-Take away the bonus to cavalry from all battlefields not labeled as open field, steppe or dessert.
-Give a cavalry penalty to armies in a siege battle.
-Nerf their infantry. they don't have to be on the same level as other factions
-Give conquered settlements a higher cultural aversion against the khuzait. This would hopefully keep them more contained to the steppes.
Obviously they are still powerful but Vlandia and Aserai were on same level.