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.
Regarding the dagger, see my comment in the Ascension thread.
https://originaltrilogy.com/topic/The-Rise-of-Skywalker-Ascendant-Released/id/71835/page/684#1569710
To the random nature of them finding the dagger: The only thing i could think of is getting rid of the chase completely and inserting an AI line in the Lando conversation that mentions a dangerous cave. Then we cut away to the Knights of Ren or something and the next time we see the group they are already in the cave. No idea if that would flow well, but it would take away the random nature and maybe even slow down the pace a bit by taking out an action scene.