About Leia knowing Rey was a Palpatine…
To me the idea just makes no sense. Even if books or comics explain it, it is a real headscratcher within the film series itself.
I don’t think it works to have a medium-sized revelation during the island scene about Leia knowing about Rey’s struggle or sense of darkness. We can see it on Leia’s face earlier in the film anyway. I think it is more effective for Luke to pierce Rey’s avoidance with a straightforward “So what?” about her being related to Palpatine. Not that Leia knew and didn’t care but that it doesn’t matter.