It wasn’t much help for any of the other issue but it prevented that sticky Shift problem which would only have complicated matters and possibly had me looking for other faults that weren’t there.
In the end a combination of quirky hardware and a stubborn emulator had me reaching for the hex editor so I could patch one of the emulators libraries that contained a built-in table of keyboard codes (something mentioned in the Psion FAQ going back to the 1990s, so not a new problem).
The good news is that emulation is now working really well, with 98% of the keys working as expected and another 1% mapped to convenient alternatives. For the remaining 1%, custom keys on the original hardware that can’t be mapped, I’ve used on-screen virtual keys (the emulator itself uses the F1-F10 keys as proxies so this was trivial in Magic DOSbox).
Thanks again for a terrific program, especially all the customisable touchscreen stuff. I’m not a heavy user of DOS games so this nearly passed me by, but I can foresee quite a few DOS applications getting a touchscreen makeover thanks to Magic DOSbox.