NICE! Thx for update!
I got a (maybe, possibly, definitely) good idea about agents. Have them be neutral. By that i mean, there shouldn't be 'your' agents but rather neutral agents that act based on their goal and interests. Etc: Merchants and Merchant guilds, their goal is to make money, they do that by visiting cities with high prosperity, and they can't revisit the last X cities they've alredy visited thus forcing them to make long or roundabout trade routes. The guilds could be a 'nation' of merchants that can accept loan requests from nobles, have a doge or a council that decides or votes, it can choose to embargo a nation / province / city so its merchants aren't allowed to get in, it has a separate treasury from its merchants so it has to tax them, which can mean low/high taxes affect the possibility of merchants banding together and leaving their guild to found a new one etc. Or you can have it be location based where instead of merchants you only have guilds that expand their influence. This 'neutral agents' system allows for ANY profession to be added. You could also have these agents be a separate pool from noble characters and allow something like 1 enthralled noble and several agents or guilds. Thoughts?
Edit: Further examples: assassins, (light/dark)priests, cults, barbarians?, mercenaries.