The problem, warb (and others), is there’s some ambiguity and you’re taking that ambiguity and assuming automatically that it must be an inconsistency, whereas you could just as easily explore all the other possible explanations for it. Just because it’s not explained doesn’t mean it’s unexplainable. Movies, and Star Wars especially, are all about the possible, not the impossible. So to go right to the latter is essentially watching it wrong.
But sometimes things do need to be explained. Again if in the next movie Han(not a ghost) suddenly walked into a room, wouldn’t that require an explanation?
What if in a future movie it is found out that sith can appear as force ghosts and kill people, wouldn’t it need to be explained why we haven’t seen that before, why dead Emperor, Maul, and Dooku don’t come back force ghosts can get revenge?