

For DIY consider a setup that supports ECC RAM to help prevent corruption. Any good server motherboard should do.
Unraid is pretty easy to get going on. That’s probably the direction I would take in your situation.
Also, if you’re not doing 3-2-1 backup now might be a good time to consider an off-site backup plan. That 4-bay Synology at a friend’s house with a VPN path would be an option for critical data. You could give them some partitioned space on there and on your new NAS to compensate for the power usage. Setup Borg or Restic and it’ll be encrypted on the remote NAS, and benefit from incremental and dedupe to minimize bandwidth usage.
From an article about the painting, it seems that the alabaster jar and faint halo over her head are references to Mary Magdelene? If the 19th century repaint was to make it a pretty picture for sellability then I could see why they wouldn’t want such a heavy subject matter.