Hi,
Ah, your getting this becuse "hhd800" looks like a video ID, so Jav-It is trying to parse it first rather than continue to look within the filename for additional patterns. Since your file name format is rather interesting, It was never really considered. I think I have an idea on how to deal with this edge case, so I'll see if I can get a fix prepared for you.
As for original filenames, there is an option to leave them as originally found (and not change them), but that only effects the filename and not the foldernames. Is that enough for you? Preserving torrent names with Symbolic Links is pretty easy on Linux/MacOS, but I'm not sure if Windows has something similar. Perhaps If I know more about what your torrent requirements are, I can try to find a solution.
As for Plex, I'm not sure because I don't have it (Since Plex is not free). The NFO file format follows KODI specifications, which is also compatable with other open source projects like JellyFin (A FOSS Plex alternative). I assume if you have an importer or program that can read KODI formatted files then you would be fine.