Pete,
I did cycle all axes and press all buttons. At that point, I noted that several buttons had assignments that hadn't existed on prior tests. (Following the installation instructions for the VRS FA-18E, I'd deleted all joystick button assignments from the FSX:SE Controls GUI.) I the closed the sim and sent you the log.
After posting that log, I brought the sim back up, and noted that FSUIPC was now recognizing controller buttons, and I was able to assign keys to them per your documentation. If that wasn't a result of the HidX55 LUA, then I don't know what caused it. Apart from that, I haven't done anything outside of following your instructions as closely as I could.
The SuperScript_VRS LUA is from hornetpits.org, intended to help cockpit builders work with all the peripheral things they use. Before contacting you here, I'd seen a recommendation at the VRS forum that SuperScript would simplify the task of assigning buttons...and it didn't work. I hadn't removed it, and probably should have.
Attached is the log from a full flight I just completed, during which all the mapped buttons appeared to work.
Assuming you're in the UK, it's got to be getting on towards Sunday evening for you. I've got leave for work soon, but if you'd like me to try anything you might thing will be helpful, I can get to it fairly early in the morning tomorrow, Pacific time.
FSUIPC4.log