Not sure if that is really your question, but you can add a new release without a tracklist if you don’t know it (so only giving title, artist and maybe label and a few other fields)
When you enter the tracklist (see e.g. https://musicbrainz.org/doc/How_to_Add_a_Release#Tracklist) you can remove the existing medium (red cross, “Remove disc”) and select “The tracklist for this release is currently unknown”
If anyone is happening upon this thread while searching for the Cantata 700, I have started a separate thread for researching information about the music for it and its successor[s].