@Joe, in fact, I really don’t mind changing it. I don’t particularly like the name “host default domain” myself, but I couldn’t think of a better option at a time.
What about instead of calling it “Create host default domain with Let’s Encrypt certificate?”** we called it “Setup Let’s Encrypt certificate for hostname”. I’m also suggesting to remove “Yes, and keep visible” option — existing users will be able to continue using it as before, but for new installs, it won’t create the false impression that this feature can be used as a normal domain.