Here are some of my suggestions.
Add unit training time.
This removes ability to instantaneously fill marshal with OP units and reinforce nearby battles.
Units have more value because they are not easy to replace...
If you wish quickly fill your army, then buy overpriced mercenaries or ineffective peasants as last resort.
Units should have upkeep in gold.
Just like food in original KoH. When marshall leave town there should be impact on royal treasury. Waging war should be expensive.
If you lose all gold you lose ability to recruit new units and you lose war. You can't go to war with empty treasury.
Build your economy first.
Upkeep is good as it is now. No need to go all the way and micromanage every man in squad... Paying 40 food/gold for 40 men in squad will just brake economy and inflate all prices. For example: Tax collector will cost 10000 Gold and give 100 gold in town...
I'm for keeping reinforcement option.
Add in town extra garrison slot that will represent Castle in province.
Give ability to call reinforcement from Castle to Marshalls fighting in province or town.
Losing castle means losing unit in that garrison.
When our marshal enter battle and and give us option to fight, retreat or lead, I would add extra options or strategies:
Fight (till last man standing), Retreat at heavy casualties, retreat at medium casualties or some other mode so I d'ont have to
constantly watch over fights to retret if I'm losing...
All (open field) battles should be direct and aggressive, if you want defensive battle then build fort and wait for enemy to attack you.
I don't see point in those micromanaging slots. I mean, how will that work? Will enemy set up their side first and then you will set it in your advantage?
Will enemy then change their side to counter your setup?
Best to leave quick battles to AI and units type algorithm. I mean, Ai should counter Chivalry with spearman's if you have them in army...