Definitely do your research if you are planning on starting any NAS with 2TB HDDs. For the most part you can only really add drives of the same size to a RAID Array (e.g. with FreeNAS), and with Unraid your parity drive you start with must be the largest disk in the system. So when you run out of space you might end up cursing yourself by not starting with larger drives. I have even regretted only starting with 4TB drives in my NAS.
You are overthinking the docker issue, it was just a software issue and broke the container in a way that I either couldn’t, or don’t have the skill to recover.