send "keyUp" / "rawKeyUp" ?

[hh]

Read again. Got it now. What you effectively want is the
(current) foreign keyMapping.

This is done by the OS, not gettable by LiveCode AFAIK.
Apple even doesn't has a file to check, Linux and Win have.
Look what they do:

https://wiki.archlinux.org/index.php/Keyboard_configuration_in_console
https://github.com/randyrants/sharpkeys
http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id=ukelele

Here is what Apple did similar to that what you have in mind?
https://support.apple.com/de-de/HT201794