Progress…
sudo qubes-dist-ugrade --releasever=4.3 --template-standalone-upgrade
tried to upgrade exactly the templates that are having update issues. So failure to run this script is probably the root cause of the problem (been awhile, so I forget if I ever ran this step). Except that my .bash_history shows that I did run the script (r4.3-rc4 at the time).
New problem however is that this process now fails to upgrade these templates because the script requires root permissions. 