First thing let us just pick a city and make merchant create a trade route after some turns. I believe it worked like that before, and it most likely was already asked. But I'd like to highlight it as well.
Second, sorting. Like what is Default Sort even mean? Is it sorted by amount of resources of target settlement? Sort by a leader, ok that may be useful I think. But what about sort by factory resources for example? By production, food resources, naval/land routes, etc.
Third, it's not really a point, because I don't fully understand the consequences of the actions, as I haven't seen any effect besides getting more money by route initiated to me, or resources initiated by me. But if it's important from which city the trade route is started, then maybe I should be able to choose it? If not, then it only affects the path on which merchant may be plundered and I still may want to choose more safe option over whatever is suggested to me using some logic which I need to transcribe first (in civ5/6 I pick both ends of trade routes).
Fourth, it'd be nice if I can trade my excessive resources (if I have any) for gold, because right now it's not clear what to do with them.
Fifth, I'd like to know available trade routes before creating a merchant. Right now I haven't found this menu (if it even exist in the first place). And lookup active trade routes easily also would be nice.
Additionaly, I think there are some debuffs for using imported resources. So it must be easy to tell which resources are imported either in trade routes menu or from resources menu (hovering on each resource and deduct origin of it - is not an easy way).
Generally, I think that I may missing something with merchants, so if somebody enlighten me on that topic and mechanics, what will disregard some of the points - I'd be only happy.
For now it looks like WIP mechanic which is strange since it worked for 2 previous games and now we have something more convoluted and less useful or clear at least.