I wouldn’t say that he was necessarily implying that Yoda was really talking about Leia all along, I think it was just a cool editing choice.

I don’t think trying to foreshadow Rey would really work in the context of ESB/ROTJ. I mean, Yoda definitely meant Leia, and I also don’t think it is fair to downplay her importance either. She is just as much Vader’s daughter as Luke is Vader’s son.

I don’t really think there is another way to downplay Leia being the ‘other’ more than it already is. As far as Leia’s connection to the Force, all we get is her sensing Luke hanging underneath Cloud City (Which could be argued as just Luke calling out to Leia), Obi-Wan conforming that they’re siblings, and Luke telling Leia she has that power too.

As far as edits changing that, I think I would only approach that in two ways.

Option 1) I would make ROTJ a stand-alone film that is sort of meant to have been the last Star Wars film, where it doesn’t matter if Luke and Leia are siblings.

Option 2) I would try to add more hints that Leia is Force-sensitive, and try to downplay Luke/Leia kissing and stuff where possible.