Check out my app for downloading subtitles from opensubtitles. It's like 10 years old, but I refreshed it and made sure it still works.
You select a folder and it does a recursive search for subfolders and downloads subtitles for all video files.
It searches by hash, takes the first offered subtitle for the selected language and puts it next to the file.
https://subtitledownloader.domagoj.net/
[EDIT] (SimplyTheBOSS)
https://www.virustotal.com/#/file/b30f4 ... /detection