(~OT) To check the id3 tags of mp3 and flac files, we need a proper tool.

eyed3 0.6.18 Just uploaded in autobuilder, should be available soon.

EDIT:
And the right sqlite command to show track's index:

sqlite3 /home/user/.cache/tracker/file-meta.db "SELECT ID, Path, Name, KeyMetadata1, KeyMetadata4 FROM Services WHERE Mime LIKE \"audio/%\" AND KeyMetadata1 != '' AND KeyMetadata4 != ''"