Good to see this scheduled, a control plane backup that depends on someone remembering is the one that gets skipped.
A few things I'd check once it's set up. There's one schedule per system and Disable-ApplianceBackupSchedule just pauses it, so I'd alert on Get-ApplianceBackupOperationList when a day goes by with no isScheduledBackup true run, not only look at the schedule. The backups go to an SMB share with a user and password saved in the config, and the docs don't say anything about how many copies are kept on the share. So how far back you can go is up to the share. I'd give that account access to that one share only and keep snapshots on the share side that this account can't delete. Whoever gets that password can delete every copy.
Last one is the encryption cert. The docs say keep it in Key Vault in global Azure, which makes sense, but at a disconnected site test once that someone can actually get to it on a bad day.
Disclosure: I'm founder and CEO of CyberSnap.