Retrieving lost work when rolling back/reverting to an earlier version

Incorporating photos and their edits into a new catalog by using the 'export as a catalog' command after having to roll back.

We have had multiple issues with LR Classic v13 - see my previous posts:

Thumbnails not reflecting edits; History panel blank for photos which have been edited.

https://community.adobe.com/t5/lightroom-classic-discussions/thumbnails-not-reflecting-edits-history-panel-blank-for-photos-which-have-been-edited/m-p/14913907/page/2#M382162

Reverting to v12.5.2 from v13.5.1 because of issues with v13

https://community.adobe.com/t5/lightroom-classic-discussions/reverting-to-v12-5-2-from-v13-5-1-because-of-issues-with-v13/m-p/14913901

We were fortunate that we had a backup of v12, which we successfully updated to v13.5.1.  As that backup was dated 30 August 2023 (none of our v13 backups worked) it did not include the last 13 months of photos and work done on them. 

No help received here re my second post (I do realise how busy you are though!), and I didn't think from reading the forums that it was possible to recover lost work when rolling back, hence my second post, but we have had some success through experimenting! 

We have managed to incorporate these more recent photos and their edits into the new catalog by using the 'export as a catalog' command when using the old v13.5.1 catalog (despite that catalog having the problems mentioned) and importing into the new catalog. 

This might be an accepted procedure but I couldn't find it suggested anywhere in the context of rolling back.  It might not work for everyone (depending on the corruption), and others here might advise against it, but I am putting it out there just in case it helps someone else who has to roll back.  We did make multiple backups and experimented with copies of catalogs, working on a different hard drive, so that we wouldn't risk our main catalog.

Of course, any work done on any other photos during the time we were using v13 has been lost.  Any collections made during this period have been lost.  And possibly other things I haven't noticed yet!

However, all seems to be working well (so far) with this new catalog, with none of the issues re previews, history panel, thumbnails etc reported in my original post. 

This has been an extremely frustrating and time-consuming process, all due to issues with v13 (especially when doing the two updates) which should not have arisen. 

I do hope that v14 will be more successful!