Do the lossless source files have the Greedo subtitles as a separate removable element? Because while you’re in there, you could make the Greedo subtitles more theatrically accurate, using subs from the Silver Screen Edition. I’ve already made rough (but good enough IMO) Photoshop layers you could use to just overlay the SSE subs on a sub-free image. You’d either lose or have to re-do any frame-to-frame differences, such as gate weave or grain, but I think it would still be a big net improvement even if those were lost. I recently updated the screenshots in the first post of the Project Threepio thread to use more theatrically-accurate subtitles than are currently available in Star Wars Despecialized, so you can see how they’re supposed to look. The “Going somewhere, Solo?” image is Despecialized with the alien subtitles from SSE Photoshopped in (positioning isn’t pixel-perfect because I was trying to cover up the old subs). The other image is just a capture of SSE color-matched to Despecialized 2.6.
This idea wouldn’t really work if you had to cover up the old subs for every frame, as it’s not a clean overlap, so the subs need to be removable in your source files.
http://originaltrilogy.com/topic/Project-Threepio-Star-Wars-OOT-subtitles/id/13794