The main issue is the lack of population and how underrated actual feudal economy is, which is based on ownership of property, lands and taxes. The problem is that you as a freelancer can go with 100 troops, defeat an actual Lord, and you complain that they dont recruit like you do, bruh, he is a lord and has several thousands of peasants under his protection at his fiefs, working for him, he should totally spawn with a bunch of troops raised to replenish his fallen army, tho they should be mostly T1-T3 troops, plus, his main income should come from taxes, war can be an enterprise so costly that it can make you lose money even when you win it, food and all takes a lot of money, and you make your best effort since losing the war can be the end of your rule, so you do everything at your hand to expand the possibilities, forcing peasants to join the army, confiscating food or raising taxes, maybe even starving your own population, all to win the war, which can totally be an economic loss on the short term. Most wars between feudal nobles are disputes on land ownership, which would give actual profit a few years after taking them.
And all of these features should apply to the player too once he becomes a lord. Which shouldnt be as fast as just leveling up your clan, you should come from lower nobility, do more relationship grinding. Right now we have this wacky economic system where being a lord and having fiefs gives really low income, not even enough to cover a reasonable defense of said fief, and with you, the chad player, making ends meet with trade/smithing/selling war loot. You main source of income should be fiefdom taxation as a lord. This is not a capitalist economy where you can just create goddamn Microsoft and become a billionaire to fund your kingdom. If at the XXI century not even Bezos or Bill Gates can earn more money that States, how the **** are we making more money than lords in a feudal economy.
War loot is overpriced and i understand that they did it this way so that there is a feeling of progression as you can afford high end stuff only when you are rich, but i think they could give the same progression if they link being able to wear certain armor or using top weapons, with your character skills. This allows even rpg gameplay for people who want to play as a lord would, commanding troops, not being good at fighting since he doesnt want to risk death (permadeath?) so he cant really use complicated weapons and armor effectively or should train a lot for it if not learned at battle.
We need population system to make sense of the world and link it to the economy, and there should be even types of population, having a 7% of population educated should make a huge economic difference agaisnt a kingdom with only 1%.
So yeah, Population and Feudal Economy, i know they wont do it, but talented modders should try to give a shot at this, could end up being a mod that would become a must have for other mods that change the setting of the game to Westeros or Feudal Japan.