Hey, that's epic, you reference one of my own threads :) However, the question I asked there was different. This is about backup/edit/restore on an AP-cluster. But you are right, I was too lazy and should have tried the search first. If I find something valuable I will report back for future reference.
Restoring a backup file is similar to the In Service Software Upgrade (ISSU) however to prevent that one firewall can override the other firewall with previous configuration, the second firewall is rebooted before the other firewall comes back online. There is a slightly longer downtime to be expected than a normal software upgrade of an HA cluster.