Nah, let’s not open a can of worms. I like the four ghosts we see thanks to John.
Understandable to not want to go overboard, I would petition to at least add Qui-Gon Jin for the following reasons:
-Every main character jedi’s force ghost from the entire main saga is now shown excluding only Qui-Gon.
-Qui-Gon was the one who discovered the way to appear as a force ghost in the first place, yet we have never seen him as one.
-It would tie in a little more significant material from the prequels and help mesh the entire saga together a little more.