After unassigning and reassigning the keys multiple times with no success, I decided to check in the aircraft.cfg file to see what settings the tailhook/wingfold/exits were configured to. I discovered that the [exits] configuration was not even present in the aircraft.cfg file, for some mysterious reason. I then downloaded a base POSKY 330V2, and copied the [exits] configuration to the problem A330. The cargo doors now open with the "Shift+E2", in addition, the main door now opens with "Shift+E" which I also discovered was not opening.
Moral of the story: Check the aircraft.cfg file to verify the tailhook/wingfold/exits configuration are present and accurately configured. Without them, anyone attempting to assign keys to open doors without these configurations in place will discover that the commands will not work.