Luke is the Jedi that is returning.
From where?
Either way you take the title, this movie is still about Luke. Nothing changes that.
Nobody here is saying that it was Anikin’s story all along. But I do think the title refers to Anikins return. Which is Lukes mission the entire film. He says it over n over.
That doesn’t retroactively change the focus of anything. It’s still Lukes story.