Well one thing I was thinking of that could help with trade is lets say lord a is selling 500 bushels for 150 while lord b is buying 400 bushels for 150 and lord b could just get extra bushels. If this was allowed where the buyer gets more then asked it would allow for more trade though likely not a ton since it requires the buyer to be paying a higher unit price to end up making it so the seller gets all the gold that the seller asked for, but if selling 500 bushels for 150 while 450 are being bought for 175 then the extra gold goes to the trader with the the extra food going once again to the buyer. Also if it could be set up where the extra food goes to the trader if the trader is lord that would be a bonus for traders.
