Hm, I should probably see about creating the "tracker-user" directory and see if that helps.

Alarm-wise, that confirms my suspicions: It was probably dst related.

Edit:
Should I:
A. Add the /var/tmp directory again? This will prevent tracker errors, prevent any issues from other programs which keep data there, but will end up with warnings about temp files not being copyable. Harmless, but annoying.

B. Add just '/var/tmp/tracker-user/cache.db'? This will solve any tracker problems, but any other apps that (mistakenly) use /var/tmp for a file that can't be deleted may have errors.

C. Add a "first run" script to the rootfs after restoring a rootfs - this would run various commands, like the tracker-reset. It may work well, -solving- extra problems(potentially), but could also be complex and/or not work all the time.