This is mostly a suggestion keeping in mind the new players we all assume the steam release will draw to the game. We veterans know full-well that the merchant is on the left, and our fortress on the right. Even knowing this, however, it took me a few moments to find any actual indications of this on the new trade screen. I imagine it might not be as obvious to entirely new players.
The only identifying information is small text, "Merchants from Etesîton" on the one side, and "Gósmerkûbuk" on the other. This text is the the same size as the otherwise detailed information below it.
Here is my proposed redesign. This is just me playing around with various changes, many of which could be made in isolation.
1. The faction identification is moved to the top, and enlarged.
Optionally tinted with faction-appropriate colors for further differentiation.
Further still, might be better to replace specific proper nouns with generic "Foreign Merchant Goods" and "Fortress Goods."
2. Value/Profit/Weight information also moved to the top. It's slightly easier to see here, and in-line with the goods' Value info.
3. Buttons are moved to a single row, and made pseudo-symmetrical.
4. Search bars are moved to the bottom. They're less in the way of more important information, and require less mouse movement between the buttons. This may or may not be relevant depending on whether they'll be active by default, or you'll have to click into them before typing, but still.
(https://i.imgur.com/ISaVyUO.png)
(https://cdn.cloudflare.steamstatic.com/steamcommunity/public/images/clans/34693670/5a1be8c13f5e11b0b8d2e3025d557cf3d572f817.png)