I'm not the person you asked but I just made a backup of my Raspberry Pi running Hermes and Matrix, but when I tested said backup it refreshed my Matrix encryption key so now I can't access my non backup micro SD install from my phone because I can't decrypt the Matrix messages.

In hindsight I should have simply rotated SD cards instead of treating one as the authoritative ones.

I agree Hermes usually works without maintenance more or less but I don't really trust these agents much and haven't found a great use for it.