@
garfield it is clear that you do not like the artist and album data created by the wider community, then as I said before simply set the default album and artist scrapers to
Local Information. This means that Kodi will only use additional artist and album data provided by you via nfo files, should you choose to do so, or nothing at all.
But I think you are wrong in that in my experience that most music library users
do care about how their music is organised and the cover art it shows.
So a quick check through your bug list.
6. Kodi is designed to work with removeable drives, hence it does not delete things from the library just because they are currently inaccessible. Hence on deleting or renaming files for folders, if you want to remove the related library entries then you need to go to system>settings>media>library and clean the music library. That removes entries where the media is not found.
5. For MP3 files the discsubtitle metadata is in TSST, tagging software may have it's own name for that but it is supported by the ID3 v2.4 format. In discussion I tend to use the FLAC/Vorbis tag name (DISCSUBTITLE), and users will need to interpret that with respect to the tools they use.
1 to 4 are all "sometimes" effects with art, and since I am not aware of any issues will need particulars to be able to reproduce. Art is also loaded in the background, so it could be that those times you are just too fast. I also have to suspect from the rest of discussion there could be some effects of renaming folders, odd tagging and not cleaning contributing. If you can provide details of folders and files that can reproduce any issue then please do.