I am back to post the solution to the problems I encountered so it can help others in the future avoid the brick wall I crashed into. My mistake was due to being a Linux Mint OS newbie. I installed LibreWolf using the Linux Mint Software Center which only offers it as Flatpak package install. After I installed LibreWolf flatpak, I uninstalled the regular default FireFox browser which was not too smart. In short, I did not know this but the Flatpak package install of LibreWolf is designed to keep this browser inside a sandbox. This was the cause to all of my HTTPS certificate headaches.
I still use my LibreWolf Flatpak as my daily driver browser. However, I also installed the AppImage package for LibreWolf and use it for only Start9 access. In short, the LibreWolf AppImage package works perfectly with Start9. And an added bonus to the LibreWolf AppImage install is how it is compatible with my Yubikey which the Flatpak install is not.
Thank you to everybody who posted in this thread. I feel I should apologize for making such a stupid mistake.