I looked a little in to the Kodi scraping and my initial thought is that it wouldn't solve your problem of having episodes not scraped or scraped incorrectly.
I looked more closely at the wiki since I couldn't determine how it would work with episodes (which need tvshow info when using separate nfo files) vs. the easier case of movies which only really have title+year+plot, and perhaps "movie set" info.
The wiki said:
> There are three more tags that should be filled in for TV Shows: Show, Season and Episode Number. At the moment these tags do not seem to be of any practical use in Kodi, but should nevertheless be filled out as this may change.
It still wasn't clear, so I looked at the original Kodi PR
https://github.com/xbmc/xbmc/pull/13106/commits/47bb0b69bb07c9a6499e00dcbcabbee66a98ef29
and the latest version of the code in xbmc/video/tags/VideoTagLoaderFFmpeg.cpp.
Acasual inspection (of avtag->key) suggests it parses "title", "director", "date_released", "title", "composer", "genre", "date", "description", "synopsis", "track", "album", "artist"; and a couple of other places where is parses artwork, "kodi-metadata", "kodi-override-metadata", and a couple of places where it uses a different context for "IMDBURL" or "TMDBURL".
Perhaps it parses season and episode and associated show details elsewhere (so you know an episode is part of a specific series).
I could easily be wrong though since I haven't done much research, just a quick look.
Perhaps you could just add tags to one of your own existing files and give it a try?
One of my concerns is that the metadata option seems to be an "all or nothing" button (rather than per-directory so you can enable it on file hierarchy you know is good).
I'm also not sure what happens if you have, say, a title in the mp4 but no plot or artwork. This probably means you don't get any art. And since they don't parse cast, it means the one feature I like of displaying actor thumbnails would presumably be lost.
It seems the best tag to add would be the TMDBURL or IMDBURL and then, perhaps, it would scrape the extra info it needed for both episodes and movies.