Kernewek (Cornish) language option missing in Launcher settings

Kernewek (Cornish) is now missing from the list of available languages for the Launcher. This is the language I have been running my Launcher in for a while, but it switched back to English suddenly a few weeks ago and I can't switch back because my language is not there in the list.

It is at 96% translated on CrowdIn (I'm finishing it up now) but that shouldn't be the issue as, for example, Asturian is on the list but is only 80% translated.

Please help so I can launch my game in my language again.