Well, all I had to do was write one more shell script up update the tags, and that’s it. Since I use nfo’s anyway (I do a lot other things that also require scripts to manipulate the metadata, not all of them for kodi), it was the simplest solution. (note scanning is orders of magnitude faster when all the data is present in the nfo) I do other things like clean up the actor/role names so that I can link to role based images (like thetvdb has) for the actor instead of displaying the same generic image on each show the actor is in, and manipulate the sort-title (to use collection name+release date), “normalize” some genres, and so forth. (I’ve got a customized skin that does a done of stuff that Kodi does not support natively)
And when it was time to display the “category” icon image, that requires the category to be in the kodi metadata so that the skin can access it. Tag was the one I chose to use for that. (the media file “path” was not useful, because it was not exposed to the skin in a way that made it easy to use as an icon link)