Aside from the friends list on your current sever, how about a friends list for Content finder itself. It would eliminate meeting once and never seeing you again thing, as well as keep you in content with players from all servers, it would keep FFXIV ARR banded as a whole.

Friend---------------- Server

Starlord ?

Gramul ?



That way when you want to party with someone that's not on your own server, you could still do stuff with them via content finder.