So as a follow-up. I decided to sort of start over and tackle two things at one time.
I rather liked the idea of having the database etc in a more practical location and noted the potential issue with Windows updates trashing the service database location so using johnvk’s updated procedure at Migrating from User to Service install on Windows, I moved things and then also changed the service to run as me instead of as the Local System account.
It occurred to me that there really was/is nothing under any other accounts that is important. Or better said, being able to backup those files from the NAS is more important than backing up data from any other accounts.
Everything seems to be running normally…