Alastair,
I did reach out to POKEYS support and they confirmed that right now they do not have the LED support in the MACH4 plugin. They did confirm that would be released soon as they are working on implementing it in the next release. Thank you for the feedback on the keyboard matrix problem, I did this several times and could not get consistent results and figured this was a plugin or MACH4 issue. Unfortunately, the MACH4 developers do not appear to be reading feedback left on this forum as many people continue to find issues but seldom do you see any questions get answered. Hopefully, things will improve as MACH4 does look promising. Thanks Again
Russ