Nah, I don’t think a 3+ hour cut of TROS would be any good. It might be better - maybe they’d let some scenes breathe more, open up the pacing, maybe even add some good scenes in; but in my opinion the film is just fundamentally broken. Its biggest failures aren’t “This needed to be explained more,” it’s that things are over explained, and the presented ideas are just arguably dumb. Bringing back Palpy? Dumb. The fetch quest that’s rendered pointless when Kyle* destroys the MacGuffin? Dumb. Ret-conning Rey’s parents? Dumb. You’d have to write a whole new script.
That said, that Ascendent is even watchable, let alone good, is nothing short of miraculous. (I’m still holding out for Rey Nobody though!)
As for Kylo’s TIE, it’s a massive continuity error, sure; but it might be tricky to change ship enough to be obviously different, while still staying in line with the First Order aesthetic. Short of designing a whole new 3D model…
If anyone wants to try, I’d definitely be interested in seeing what they come up with!
*That was autocorrect, but I’m leaving it.