1) add realm column to market. we know noble X of region Y is trading. but you don't know what realm that is without looking it up... unless you are familiar with the region names and can recall it off the top of your hat. - does not have to be its own column (eg.. can be region Y, realm Z as 1 column), but own column means you can sort by realm. probably more useful.
2) add sanction/trade partner status. so you don't have to have a full blown alliance or war for the purpose of utilising the allies only / no trade with at war realm trade functions. presumably as part of the revamped treaty matrix. or unlikely as it is, in old diplo matrix.