Since it looks like there won’t be any deleted scenes, to follow up with Krausfadr, would removing the Mustafar part and have something in the crawl that talks about it simply, like “Kylo obtained the key to find the source of his master’s power/ Haunted by mysterious whispers, KYLO REN has obtained the key to reveal the source” or something like that. (I am TERRIBLE at writing)
We don’t have to label it as “Sith Wayfinder” since the movie later tells us what it is.
I just suggest this IF having the opening scene on Mustafar raises more questions or whatever and things would flow better without it with a “simple” sentence in the crawl.