I'm not sure where the best place to do this is, but I have an idea for a feature request. I think this would be quite beneficial to anyone on 6.12+ and using ZFS for their cache pool where their appdata directory lives.
The feature would take advantage of ZFS snapshots to enable backing up of the appdata directory and xml without shutting down the containers. The procedure would be something like this.
Check for unraid 6.12+
Check if appdata is on a ZFS filesystem AND in its own dataset
If so, take a snapshot and give it a unique name generated by the script
Substitute in the snapshot path into the appdata location and then run the script as normal, but without shutting down the containers
At the end of the procedure the MVP could be deleting the snapshot so they don't pile up. But a more advanced version would incorporate some basic snapshot management for the automatically created snapshots.
If i can get some time I would love to take a crack at this, but that's in short supply for me now. I figured I would throw this out there in case someone else wants to work on it.