I think these are really good points and ideas. RotJ really works at the end because Luke faces so much temptation. Rey has a tending towards the dark but that temptation could really be emphasised.
Speaking of the dagger, now that it operates by whisper rather than the absolutely contrived pointing, it’s remaining flaw as a plot device is that the good guys stumble upon it in an absolute quirk of chance. Perhaps it could be implied that it’s somehow drawn Rey to it- either through Palpatine’s machinations or its own.
Maybe after they fall into the tunnels, after Finn says, “Which way out of here?”, we could change Rey’s off screen line from “We have to hurry” to something like, “Wait, I sense something this way…” after she turns away from camera.
And like Dimitrios mentioned, perhaps we could squeeze in a line from Lando about the caves, but I’m not sure how it could/should be phrased. If Lando mentions the caves, then the audience will wonder why him and Luke didn’t check them if Lando knows about them. And I don’t think there is enough time during their scene with Lando for him to really rationalize it. Maybe he could say, “Maybe he fell in the sinking fields”. Again, may run into the same problem.
I like those write ups btw Starkiller! Really need to play around with making clean audio for those two scenes so people can play around with them.