As a counter thought Hal, which you do bring up good points … There is no explanation, in the movie (quite Jar Jar with your books/EU outside of the movie 😉) about Kylo showing up. The Force moves with the plot unfortunately, so even if he does show up without explanation … it doesn’t matter. The only tangible explanation would be the whole Dyad thing. After the Star Destroyer/Hanger/whatever scene … we see these two more connected than ever. Maybe that can be the explanation without having to explain it? Sure. Could Palps have told Kylo behind the scenes “Prove yourself loyal, kill Rey at the DSII where my Wayfinder is you punk.” … sure. Again, remember, the original movies gives NO explanation … so we just have to go with it. Kylo is Rey’s stalker after all…
As for the Rey thing … if there is some solid vision during the scene where she grabs the dagger and shows some CLEAR imagery … and use the Finn line from earlier about him talking about Endor later, as if Rey told him off screen … it can work. I think the key is using a good vision with solid images that points to Endor that will sell it. We literally can use the audio of Finn using the word Endor … which I think Sherlock did some tests to sell it when they were on Orchi’s ship. It works, especially for a movie that already relies on outside sources to explain things … this edit is actually TRYING to make the important things happen in the movie for explanation and not rely on books or tweets to do that. Oh my.
EDIT: Also, I want to give another nod to Nev with what he has done with the castle stuff. It is workin very well and is connecting the dots. Using just that shot you have done (and maybe adding 3 FO Ties) with the first shot Poppa did will blend great. We see an overview of Mustafar that shows more green, and with the next shot we clearly see trees and plant life has grown in Mustafar since the last time we saw it in Rouge One (with Vader not being there … pretty much life has found its way AKA Jurasic Park Reference 😄) and it really helps make sense of things when we see Kylo and the battle on the ground.
My Goodness, it is kinda irritating what we got from this movie without some of these key things fan editors are having to do … to make things make sense. LOL.