I'm not close to GL Leia, but I fully endorse the idea that the requirements for GLs are the hurdle.
We've put in the laborious work over months. The event should be a fun celebration of the SW story related to that character. There is no game balance reason why someone who completes all the pre-reqs shouldn't be allowed the character, so repeated failures don't serve any overarching purpose in game. They only make the game less fun for players.
That said, and I don't know it will work, but I support what KDC said. Vader has always required landing debuffs on his enemies to be his most effective. If you can't get TenacityUP, then modding for Ten is an obvious thing to try. Maybe it will help you feel less tortured while waiting for CG to figure out how to prioritize fun.