Thanks a lot for the answers. Will try to find better forum for x265 question.
I've wiped off my exploded brain from the floor after reading through the subtitle explanations
The zidoo x9s has in its proprietary media player a bunch of options how to display subtitles with 3D. I have to revisit the options, maybe i understand their effect better after your explanations. It sounds to me almost as if i should not try to convert to 2D subtitles, but keep 3D? subtitles with a fixed depth that makes them stay out very much in-front so they never overlap... Lets see. Burned in subtitles definitely d not make sense to me where i would hope to have my the RIPs of my blu rays be at least dual language. The extraction of forced vs. non-forced subtitles is on the top of best features in BD3D2MKV3D.
I have seen the Chinese Blu ray ripper being able to convert individual chapters without noticeable lead-in time that would otherwise be required to decode the rest of the move. Also Blu ray players can of course start decoding at chapter boundaries. But of course, i have no idea if any of the toolchains BD3D2MKV3D uses would make that easy or impossible. Should be reasonably easy though to modify the CMD as you explained to quickly run through different encoding options after a full decode is on disk. Optimizing h265 parameters for example.