Instead of broken formations you could either introduce a "rout" feature that does the following:
- routing squads/battalions cannot be controlled by the player
- will no longer attack enemy units (unless it's surrounded and cannot run away)
- will automatically try to reach a nearby player town center and can be reinforced back to old strength again for resources
Similar with economy. It would be way easier if population, food costs, women/citizen soldiers and the resources would