On a fresh install of the OS and Kodi and it’s now working. I guess somewhere along the way my keymapping must have gone wonky. Next step is off to the eOS support to find out how to add the command so I can start Kodi with eventlirc from the dock. For now I’ve got it set to run the command at startup which isn’t ideal but more accessible than going into terminal every time I want to use Kodi, seeing as that’s the main function of this machine.
Thanks for all your time and help. I think part of my confusion along the way was that the post you linked to OSMC remote mapping on KodiBuntu has an outdated package for eventlirc, so with the up to date one you gave in post 14 I think after that it was just whatever I’d done previously was stopping it from running as it should.
Update: on the off chance anyone comes across this following a similar path, I created an icon for launching Kodi with remote support thanks to a prompt from the eOS stack exchange here launcher - Alter application icon to execute command? - elementary OS Stack Exchange which I think should work in general for Linux, or at least Ubuntu based versions of Linux?