Would it make sense that Jaikoz would optionally generate Last modified -date custom tag to all tracks OR copy this information from Musicbrainz and Discogs, after it has updated metadata from MB and DC?
Next time you go through your library with Jaikoz, and want check if the metadata has been updated at MB or DC, you could just check the “Last modified” date against the date at MB and DC, and if same you could ignore that track. If there has been recent changes, you could update the metadata.
It would be a nice option as well, that if no changes were detected, Jaikoz would automatically close these files. After you have gone through a huge batch, only those with changes would still be loaded. This would speed up processing significantly.