With ESB I don't think it fixing much that is broken more that the film is so beautiful in so many ways that Ady wants pay tribute to it by giving it a loving clean and a nice new frame.

As always the Revisited series are an attempt address the problems with the SE not with the theatrical version.

In terms of the OT ROTJ is broken in every version and may actually give Ady a more free canvas to play with than working with the first two films which are held with such high regard.

That said, just look back at the ta'do with "Lando Lives" to see how frustrating changing ROTJ might be in the future.