[pkscout]

Regarding the "MBID-table" I realized that the things are probably different than I thought. Since I do almost only streaming those artist (for which i do not have my own music) are not in the Kodi database right? I wonder how the handling of the artist-code in the cache folder is done? Are those codes managed by AS or by Kodi?

Yea, the streaming artists won't be in the Kodi db at all. For streaming artists, AS handles everything. AS uses the artist name (if it can figure it out based on the information the stream provides) to create the cache folders and then hopes that either theaudiodb or lastfm will return a musicbrainz ID so that you can use fanart.tv images. The actual names are hashes of the artist name (using Kodi's internal hash mechanism), and that was done early on (pre my time even) to avoid unicode name problems. At this point changing that would be really problematic.