While I was on the road my Imatch database developed a critical error (Severe Database Problem Detected!) and suggested that I go back to a good backup version. Unfortunately, my backups were on my home computer and not available. Although I was getting an error message and clearly the databas had problems, everything appeared to work fine, and I didn't have many options, so I continued to load files into the database. Now that I am home I can get a backup but would like to save the categorization that I did to the new pictures that were added after the db went bad.
Is it possible to do a category export on the bad database, move back to a backup database, reload and rescan the new files, and then do a category import to get the categories reattached to the new files? There are a few hundred files that were added after the db went bad and I would prefer not to have to manually re-categorize them if possible.
Yes, this is possible. You can use the Import & Export panel to export your category assignments from your notebook DB and import them into your home DB. See https://www.photools.com/help/imatch/#impexp_groups.htm (https://www.photools.com/help/imatch/#impexp_groups.htm).
As always, make a backup of your production DB before importing the assignments.