I mean, the SEs and PT also have the ‘George Lucas Seal of Approval’. This site wouldn’t need to exist if that was actually any meaningful indicator of quality. Sure, as the creator of the franchise, everything he didn’t work on is essentially ‘fan fiction’ (be it the old or new extended continuities) but so are all the excellent fanedits and other projects here.
Re: Rey’s ‘power level’: I think a lot of the disagreement comes from a difference in understanding of how the Force is supposed to work. A lot of Yoda’s teaching in ESB - ‘size matters not’/‘only different in your mind’, ‘do or do not, there is no try’, telling Luke ‘that is why you fail’ in response to his disbelief over the X-wing being lifted out of the water - suggests to me at least it’s more of a binary thing than a linear power scale. Yoda wasn’t entirely just screwing with Luke, right, he really did think it could’ve been possible for him to lift the X-wing himself after what is, in the most generous interpretation of ESB, absolutely no more than a month of training, so long as he truly believed he could do it. After all, that’s how Luke wins in the first movie: he’s had less than an hour or so of training by Yavin, but the whole idea of the climax is that just by truly letting go and putting absolute faith in the Force, he lands the shot. Not because he’s spent six years training in the specific technique of Force-Enhanced Torpedo Accuracy.
I know the prequels jam that all up somewhat with midichlorian counts but that’s lame (and for people who are deeply concerned with how many magic Force bacteria our protagonists have, TROS does go out of its way to cover who Rey inherited her midichlorian-rich blood from, at great expense).
Regarding lightsaber fighting specifically, the movie shows us Rey is already well-practiced defending herself with other melee weapons, and in TCW (which has the ‘George Lucas Seal of Approval’) and also in other new continuity media like Rebels and Mando we see non-Force users wielding lightsabers/the darksaber, so presumably Rey’s ability to hold her own against Kylo (who is injured and not actually trying to kill her yadda yadda yadda) with one in TFA is just transferring over that general skill. If she was accurately deflecting blaster bolts with it or pulling off lighting-fast prequel-style choreography that’d be a stretch, but IIRC she basically just swings it around.