I agree the line about Leia knowing Rey was a Palpatine all along should be removed, leaving it just creates more questions than answers. How long did they know? Why did neither of them told her? This is never adressed further.
When I [and I assume, many others] watched it at the theater I took it as both Luke and Leia knowing from the very beginning, and both keeping it secret from her (much like how Obi-Wan & Yoda hide Vader’s true identity from Luke). This would mean Luke was just pretending not to know who she is on TLJ, ruining what’s imo the best part of that movie.
I have 0 editing experience, but I made a mockup to show how the scene could work:
https://vimeo.com/429851092
pw:fanedit
I think it flows well. Rey’s expresion after Luke says “Because you’re a Palpatine” could be interpreted as her feeling sad/ashamed/scared that Luke knows her identity. By removing those lines it seems like Luke has just found out alongside Rey, and he shows how much he’s grown since TLJ by staying calm and trusting Rey, whereas in TLJ he is startled and flees after she fails her first lesson.