I’m still reading through all the discussion here (ROTJ is my favourite OT film, so I’m excited to pick it apart), but a tiny note: the subtitle font for the aliens is Franklin Gothic Demi Bold.
And if that font isn’t available, try Franklin Gothic Demi Cond as an alternative! I used that font for my prequel edits, and it looks almost identical to most Star Wars subtitles! Just a heads up for any other fan editors having this problem.