No, what I meant was my previous custom civs from GC4 were all "greyed out" and could not be used in Supernova. However, if I edited those civs, resaved as a new civ, and then exited and restarted the game, that new version of the custom civ becomes playable.
Based on another forum post, I think it has to do with early access disallowing the previous civs to be used. I guess in Supernova, new civs must be created (or re-created from old).