A very useful feature would be:

A browser extension or media player feature (e.g., in VLC, BS.Player, or Subtitle Edit) that can automatically detect your video file of The Passion of the Christ and download the correct Romanian subtitle (.srt or .ass) from open subtitle databases like OpenSubtitles.org or Subs.ro .

This helps you avoid manually searching for matching subtitle versions (e.g., for the 2004 movie, director's cut, or dubbed vs. original Aramaic/Latin audio).