Well, if you are actually thinking that a character showing up as g12 in a galactic challenge means that they have g12 stats, clearly that is nothing but naivete. Those are high relic characters disguised as g12, and it always has been that way. The galactic challenge is doable at t10 with a GAS lead jedi team, so it does not require a GL. That is about as reasonable as they get these days. And besides, if you are actually spending money for the purpose of completing galactic challenges, then it seems you just have a complete misunderstanding of how this game works.
There are real issues with this game right now, but the fact that one particular team that you have reliced is not strong against the current galactic challenge is not it.