Personally speaking, I find that having Leia die on screen in the first five minutes (and accidentally implying it could be from a heart attack) to be kind of icky. At least with the theatrical version (and more so with Ascendant), Leia dies in a pretty Star Wars-ian way and this is already after the Frankenstein’d version of her character had been appearing throughout the movie.
I honestly think the best course of action to go with in not having Leia in this movie (and one I was pretty sure they were going to do before they announced they would be using prior footage) is to just have Leia die in between films. Mention it in the crawl, establish she had been training Rey, and say that it might be from what happened to her in TLJ if you want. I mean, it’s kind of shitty, but obviously the reality of what actually happened with Carrie and how the filmmakers had to scramble to figure out how to put her in the last film is shitty. 😕