I think what you’re describing for #1 and #2 is partway to an SDH subtitle. i.e. cues for things you may not be able to hear clearly. While I’d happily accept SDH subtitles for non-English languages, I’d have to rely entirely on others to do the translation work (the commercial subtitles generally don’t do this). You could use the English SDH subtitles as a template, just finding the SDH cues and translating them/inserting them into the existing subtitles. The character names would have to be localized to the current translation. No universal abbreviation system would work (think about languages that don’t use Latin characters).
There are a couple Uncle Owen exchanges that are just very dense, and rougher on mid-dialogue line breaks than anywhere else in the trilogy. I’m more likely to solve that problem through retiming than anything else, but only if it’s a noticeable improvement and maintains readability. I’ve even dropped one of C-3PO’s lines (“Shutting up, sir”) in that particular exchange in an attempt to give the other lines more space. It’s just… a lot of dialogue in a short period of time. I see what you’re doing, but I’m not sure this is the way to do it, in non-SDH subtitles, at least.
For #3, you’re definitely not the only one who’s interested in this, but this is too much for this project. These subtitles are designed for the English audio only – adding one more supported audio track, with different translations and even different timing (stormtrooper voices don’t always line up at all, because there are no lips to sync), could theoretically double the size of the project, and then double again for another dub. I definitely recognize that if you watch, for example, the Italian dub with Italian subtitles (or the Italian dub with Croatian subtitles, etc), the dialogue won’t match. That’s a line I drew a long time ago for this project, and I’m not willing to step over it. The project goal is to provide the best possible translations of the English dialogue, and that’s all. Dub translations often prioritize things like lip-matching, so it’s possible no “best English translation” subtitle would match in any dub translation. There are language-specific preservations (Krieg der Sterne, Geurre Stellari, etc), and it’d probably make more sense to pair this type of subtitle with those projects. It’s a good idea overall – I know I occasionally watch films both dubbed and subbed in English, and I don’t like when they don’t match, even though I know why.
For #4, I like the thinking outside the box, but no. Too weird 😉