There is currently no command to list the existing mob spawns on a map you’re making, so if you haven’t written the names down or discarded/lost the list of names, you effectively become unable to alter the position of mob spawns on your map.
Currently, the only workaround is directly contacting somebody with access to the DG files, which is rather suboptimal.
There exists however, a command to list player spawns, so I at least wouldn’t immediately see why this wouldn’t also work for mob spawns, except for maybe it being a niche use situation (though the same applies to the command to list player spawns).
We plan to implement this suggestion, which is now marked as accepted and closed to release the votes. Once this suggestion has been implemented, a dev will mark it as implemented, and a final reply will be posted so that everyone is aware.
This is listed as “” on the development timetable: