Thanks, @olivierlambert . It looks like the restore mostly worked. There was one main issue:
After I restored the configuration, all of the plugins I had had to manually configure when I first installed XOA (auth-ldap, transport-email, and usage-report) were all disabled. When I tried to re-enable them, they failed with the "plugin not configured" error. However, when I expanded their configuration, it was still present thanks to the restore. What I had to do was manually change an arbitrary field in each plugin so that I could click the "Save Configuration" button. Then I was able to re-enable the plugin. Probably a bug I should report?