This is just my opinion and some of the points has been touched by others in the thread either in the same line of thoughts or opposite.
Taxes:
Taxes is imo rather small, but I mainly think that a governor should have a greater influenze on the economy of a town/castle both in terms of prosperity but also in terms of taxes paid.
Workshops:
Passive income that needs a buff. It may be just me, but workshops has no bearing on the items being produced in the town, if you make a smith in a town it should have better hightier equipment. Another thing I'd like to see is the ability to "order" an item crafted in the shop reflecting the culture of the town and it would give a bit more usability to workshops.
Mercenary contracts:
I think the contracts should better reflect the quality of the army that's being contracted. A buff early ingame would make the player better able to field an army that reflects the clan level better.
Towns: Town prosperity is too affected by issues in the town or bound villages, basically if you create a "safe" area far from the frontlines, that area should reflect the increased security with less looters/hideouts and in general fewer issues. Towns should also be better linked, basically we have rough areas of production in the game, but this could be elaborated further with fx. rare ressources needed for fx. crafting/ordering special items.
Shopitems:
Greater variety, more locked to culture, high-end items should randomly appear even in low prosperity towns.
Caravans:
Should have a greater impact on a towns econ when a caravan gets hit. Should have larger profitmargins reflecting the investment/risk/reward the player need to make in order to have a caravan. This isn't so much an issue later on ingame, but early on the caravans are often net deficit makers. Atleast for me, but I may just be bad at trading
Crafting:
First off a critical critique: Random number generator is purely something developers insert because they either lack the imagination to implement an interesting alternative or is too incompetent to develop a deeper and more immersive system. RNG is basically the laziest solution and I give no points for it. Remove RNG entirely, excepting perhaps in the fine/mastery/legendary end result. It's primarily the random nature of getting more bp for items.
Secondly: The items are actually pretty well diverse and usable for different situations, it's not always the best option to take the highest tier handle fx. and I really appreciate that nuance.
Thirdly: Make it deeper. Have a bowyer skill-set, an armoury skill set and req the player to own and operate the appropriate workshop in order to do the crafting (and have crafting fixed in the town(s) where the workshop is.