Dunno about the OP but I'm very aware as I'm not an english speaker.

I still don't want anything as unpredictable as Unicode in my code. How many different encodings will display as the same variable name and how is the compiler supposed to decide?

If you're thinking of comments and user facing strings, the OP already excluded those.

And those are not programming languages, or at least not the C programming language which only needs a very limited character set.

What; like APL‽