Are you allowed

Are you allowed to use galactic conquest with new races from mods like Earth Alliance, The Borg And The Outsiders League? (WIP)
I’ve tried it with one battle and it works.

Yep, but your fleets will not be saved for future encounters of other players, Galactic Conquest is programmed to save the deployments of the players (when using vainilla races) then it use the deployments of other players against you, and the inverse.