Hello,
At first, I realize that it is a big job to do all of that. Thank you for this work.
I've tested some features as you asked.
I Have found the right settings for getting what I desire :

- Checking "Crawl thumbnail"
- Setting "thumbnail filename mode" to
Package name
- Checking "Crawl subtitled burned in versions (partial/forced)"
- Setting "Define how this plugin should pick your desired qualities" to
Best quality
- Setting "language selection mode" to
Auto
- Setting "what to add if based ..." to
Best quality
- Setting "select file name scheme type" to
Legacy
- Setting "select Package name scheme type" to
Legacy
All seem to work perfectly : I get the thumbnail in the version I expect and the file in french version, except for files which exist only in original version with subtitles. In this case, I get german subtitled versions too. So, I delete them by hand and all is correct.
As my computer is desperatly old and slow,

I didn't test every case. The variety of files and cases is too big. However, sometimes, I noticed some weird results. But I am not sure.

I'll try to get back later on these cases.
So long guys and good job