Regarding native subs, don’t the Krieg der Sterne projects typically include German subtitles (equivalent to this project’s “native” subtitles)? I honestly don’t know. It seems that certainly the subs should be available from either Project Threepio or Krieg der Sterne preservations, it’s just a matter of where the best match is.
On this whole ImageMagick+Pango tangent I keep going on about, it’s looking increasingly likely that I’m going to be (again) ripping large parts of this project out by the roots and redoing them before the next version (likely version 10.0 if it actually works), so never say never about anything.