I really recommend for a clear/visible BIG mark on the terrain/title-map your char need to go so the game recognize that you did “find” the dark elf’s villager, right now i did go there and talked to every one, and moved in every terrain/title-map in their cave/base, but the game still do not let me recruit them.
Same for gnomes trade route.
Or better, change it so if you talk to ANY one of them, game mark that you did “find” them.
I ASSUMED you have to find and talk to the “Village Elder” of each ally tribe to get them to join you, I always run around trying to find em before leaving. It makes more sense that you would need to talk to the Leader of the group before they’re willing to let you basically lord over some of their people.