Yeah, whatever other problems there are with ROTJ, Special Effects aren't one of them - I think ROTJ is the absolute pinacle of optical visual effects and may be the most realistic looking space battle of all time, including CG ones. And only a couple of shots have been re-comped for the SE - most of the space battle you see on the BD is the original compositing. And it looks 100% more real than any of the visual fx shown in the TFA trailers.

And those composites you pointed out actually look really good for the time, especially the Tatooine ones - I've seen much worse greenscreen compositing of people in modern blocbusters. The hangar matte is admittedly not great but that's definitely the exception.