What I would like to see is a system where settlements (including your own fortress) can offer specific exports (such as 7000☼ worth of red silk, or 1000☼ worth of stone crafts with at least exceptional quality), and when trade meetings occur you view the offerings of various settlements and request specified amounts of those goods. The offerings of your own fortress would be suggested by the bookkeeper based on the previous year's production, but ultimately the user gets to choose them.
Rather than being vague suggestions and setting of prices, trade agreements would be a contract where you guarantee you can provide the exports that have been requested of you, and you guarantee that when the caravan comes around with the goods you've requested you will be able to afford it. Failure to fulfill agreements would affect entity relations.
Yeah, I personally have always rather preferred something more like the system in Pharoah. You have a screen where you say that you'll buy up to such-and-such an amount of goods that the traders from one port or city are willing to offer you, and then you slate up to such-and-such an amount of goods to be made available for trade every year.
The actual bargaining and trade takes place without you having to drop everything and wade through a menu for an hour to manually select each and every individual bag of sand you want to buy and toggle each and every pig tail sock and microcline mug you want to sell.
Something like that would also be of much greater use if we get a caravan system and tavern where we don't have just "The Autumn Caravan", and instead have fleets of merchants who stop by every other week, and just do some trading and some boozing in your tarvern while in town before heading back off on the dusty caravan trails.
That way, as a player, I can just say "Buy every single ____ metal bar that comes by, and just get rid of these stupid microcline mugs and pig tail socks in exchange for that."