One way to better set up the redemption arc would be use more TROS scenes, like opening with Kylo travelling to Exegol, and threading more of the Palpatine plot through the film. Instead of Kef Bir, this is where Snoke’s throne room fight could structurally be, since both battles kind of achieve the same thing. You could possibly cut Rey out of the Crait sequence, and suggest she stole Kylo’s TIE from Snoke’s Star Destroyer and took it to Ahch-To just after Luke died.
I’d have to look closer to see if that would work, but it would allow the throne room fight to be the end of the second act, and the fight on Exegol to be the end of the third act.
Good thoughts. I definitely think putting in Kylo’s journey to Exegol might be good. But I really don’t want to put in Palpatine for various reasons. The biggest is that it makes the film too packed for the run time. But also, it’s one of my goals to keep the story closer to something that doesn’t retcon much from the original films.