Lol, yeah, haha! The simplest thing though is to remove the whole training thing in Revenge of the Sith. Here’s the question: Is it needed?

If you remove that, it takes away the whole: "How did BLANK turn to a ghost without/presumedly without such training?

The audience can then assume this if watching the movies: Jedi turn(or can turn) to Force Ghosts/Voices and Sith kind of have a reincarnation/Transfer/Avatar style thingy. No need for further explanation since you see it for yourself.