Looks like a closed source Discourse and Reddit merge…
It’s great that you want to move to Discourse, but sadly I cant be of any help. It may be worth it restarting and setting up a new Discourse instance, because I have no idea how Tribe works behind the scenes, and it’s closed source oto, right?
You should just email all of the users that you switched forum softwares and to sign up again, and if you want a familiar theme try Fakebook, or Fakebook Pro
Again, sorry I cant be any help, you will love Discourse.