The infocards don't make it obvious what my income is from trading, where the caravan hails from (although I think the white text was trying to tell me where it was from in the non-trading case), or where the caravan is going to vs. coming from:
I'd recommend using/adding language similar to: "tariffs: x%"
Or perhaps this information is just what the Caravan is 'carrying' not what the sovereign's income would be from the trade.
it would also be nice to know how long (turns wise) the trading trip is for the caravan, and where the caravan is at in the trip, to gauge how profitable the route is.
for a final example, how about:
"Trading: Norarar to Abriill" *Bold for home city
"Carrying: 95.48 Gildar, 2.2 Metal"
"Tariffs: 10%, 9.55Gildar, 0.22 Metal"
"Arrival: Abriill in 2 of 3 turns"
"'Moved by the Invisible Hand(tm)'"
I'd use my Photoshop skills to make it sexy for you but I think you get the idea.
Lastly, and most importantly in my mind, trade is not a legitimate function of government as people can do their own trading just fine, thank you. I as the sovereign should not be building caravans and telling them where to go, just give me a cut of their trade goods for ensuring the safety of the roads and providing them a place to trade in town. The population can take care of their own trade when the trade route is sufficiently pacified (or they can try when it is decidedly not pacified too if that creates a fun highway robbery mechanic), and sufficiently profitable for the traders (i.e. tons of trade between big cities with differing resources/knowledge, decent trade between big cities, less trade between cities and small outposts, almost no trade between small outposts). You can also tie into the equation the number of markets/merchant areas you build in your city as well, and make them generate revenue from a small base (internal trade) + revenue from tariffs based on external trade. And if your trade lines get raided...poof goes that cash flow (and the brigands get caravan loot).
In short, I'd like to play the part of a real sovereign who rules over and interacts with an independent (lifelike) world, than a micromanaging megalomaniac that controls every aspect of existence.