Yes... that was really annoying bugs of some men running away from their own units, and start creating mess when you send them in the city... but that's just the part of the game anyway.... It's Medieval, and all did you want as a soldier is an earlier chance to loot houses and rape women.


some simple solution to the siege bug...
1. Use siege weapons, not only to break their wall, but to destroy them... I usually use 4 trebuchets or more, yes they are slow to march on campaign map, but they are pretty useful anyway.

2. Order your unit to move only in reasonably short way... ordering them long way in cities just take the mess.

3. Use cavalry to flank in cities, they had better cohesion than infantry anyway... Use infantry just to hold them.

But I think that way would represent Barbarian factions (impetuous units), eastern levies, and militia skirmishers better in EB2, the primary line army could had disciplined, highly_trained, as these attributes gives them more cohesiveness in M2TW...