I have 3 languages/keyboards installed in my system, for switching around with alt-shift. English is NOT one of them.
When I start openxcom - and as far as I can tell, only then, no other program does this - English gets added to the keyboards I can choose with alt-shift.
To make it even more weird, the English option does NOT get added to the "language preferences" list. If I go into those options to remove it, I need to manually add it first, and only then can I remove it. Then it disappears from the alt-shift list as well, at least until I play openxcom again.
This is obviously not what I would call desireable behaviour from a game...
Other info: my system is Windows 10. Openxcom display language can be English, or it can be something else, it doesn't stop the behaviour.