[hoschilo]

Ah, I think I must have misunderstood how it works - doesn't it look for an MBID tag in the playing file first and then if it doesn't find one, look for a musicbrainz.nfo file and if it doesn't find that does a lookup at theaudiodb to see if it can find an MBID for the artist name?

Here's the order:

Ask Kodi for the MBID (i.e. tagged in the music).
If no MBID is found, try and get file from theaudiodb (or use the existing one) and use the MBID from there.
I no MBID is found, check the musicbrainz.nfo file to see if there is one there.

Could you consider to add extraction of MBID from the lastfmartistbio.nfo as an additional step. I just realized that in this file MBID is also available (maybe not for all). So grabbing art from FANART.TV would also work if TADB server is down. I would also suggest to "make" the file musicbrainz.nfo in any case, and to start accessing databases from this point. In some cases when no MBID or even wrong tag was found from your standard procedure - it would be easier for the user to edit manually this file.

Maybe you could even think about an additional functionality (AShelper) where a table of missing MBID is generated in which the user can add the missing "mbids" manually.