A release which combines releases from several other release groups into one new release should be a separate release group. This includes box sets and “2 in 1” releases.
As in all the best recipes - here is one I made earlier…
Or in pictures (a different script, but you should get the details)
Userscripts can be great at automating tasks… but always need to be checked. They can be a massive time saver, or they can make a huge mess in equal levels. Never trust 'em to be perfect.
To add to that, when importing from Discogs, track capitalization normally needs to be changed as they capitalize all the words over there. You’ll also find misspellings occasionally, track length differences, or the wrong artist credited for a release. I’ll often use Discogs to seed the information for a new MB release, then I verify as much as I can with cover art or the cd.