Repair doesnt work was the test to see if missing dlist and dindex files could be regenerated from database.
Automatic backups stopped AND rolled back when restoring drive image of Ubuntu-partition was the test of setting a database to an old copy, then trying repair. In addition to deleting newer backups, it had various other issues that I’d forgotten and didn’t look at closely at that time, so I’m liking this idea less than before…
You can also look at the post just above mine for an example of a full-scale disaster due to database mixup.
This would be safer, but I can’t think of a simple way. That’s a pretty unusual (but perhaps useful) capability. There are awkward solutions such as duplicating the backup (perhaps even to local disk, using rclone), and then setting up a clone of the original backup on another system (don’t mix types, e.g. Windows to Linux) to get the dlist back, to move to the live system, but that seems pretty extreme, given your redundant backups.