

You have enough failures on each disk to make me suspect an issue with the usb-connected drive bay. I ran into similar issues with a cheap pci-e sata adapter, where little hiccups and latency in the communication layer would cause zfs to take disks offline randomly. Read, write, and checksum errors would slowly accumulate across all of the disks. Switched that machine to a proper enterprise hba, the issues vanished, and the disks are all healthy 3-4 years later.
Where Should We Begin? is a podcast by the psychotherapist Esther Perel, where each episode is a full couple’s therapy session with an anonymous couple. It’s nice, and sounds like a match for your question.