In my opinion mounted combat feels a bit clunky and weird compared to warband especially with 1H Weapons and it influence AI controlled Cav to.
The Main issues for that i see in:
1: Lance length and griping, some lances are too short or griped somewhere in the middle instead of the end which makes their range when couching too short and Ai Cav does rarely use couching at all
2: generall hit detection, sometimes it weird you hit somebody with your lance in the body and kill his horse or your sword passes through someone and does no damage, you can see similar behavior from the AI Cav too this is especially bad with 1 Handed Swords which often dont hit.
3: many AI 1H Cav seems to have way too short swords
4: Character Size: seemingly having a larger then Standard Height has bad influence on mounted Combat as hitting stuff becomes harder with 1H Weapind and you need far longer swords then Normal
5: Weapon length is far too important making things like Maces and axes often even worse too use on horseback as they have a length below 100 in most cases