After a little more tinkering I've found the problem. Simply deleting the preferences plist file (which appears to be $HOME/Library/Preferences/org.qelectrotech.QElectroTech.plist) was not sufficient because MacOS Big Sur appears to cache the information. To fully get back to the original configuration, I did the following:
rm -rf ~/.qet; find ~/Library -iname \*qelectro\* -exec rm -rf '{}' ';' 2>/dev/null
and then rebooted. Seems a little crazy, but now I have the original configuration. Given Laurent's response I would imagine that simply deleting the plist file and then rebooting would have been sufficient.
Here are the files I see after I opened QElectroTech once:
fahnoe@luna ~ % ls -la ~/.qet; find ~/Library -iname \*qelectro\* 2>/dev/null
total 48
drwxr-xr-x 6 fahnoe staff 192 Oct 9 12:21 .
drwxr-xr-x@ 101 fahnoe staff 3232 Oct 9 12:21 ..
-rw-r--r-- 1 fahnoe staff 2437 Oct 9 12:21 20221009.log
drwxr-xr-x 2 fahnoe staff 64 Oct 9 12:21 elements
-rw-r--r-- 1 fahnoe staff 20480 Oct 9 12:21 elements_cache.sqlite
drwxr-xr-x 2 fahnoe staff 64 Oct 9 12:21 titleblocks
/Users/fahnoe/Library/Saved Application State/org.qelectrotech.savedState
/Users/fahnoe/Library/Preferences/org.qelectrotech.QElectroTech.plist
fahnoe@luna ~ %
--Larry