There is no requirement that the code you see/edit is the same code that is stored and compiled.
Just as an editor can show → for -> and λ for \ if adequately configured, it can also show 'если' for 'if' and 'Функция' for 'function' (or, say, the chinese equivalents) while keeping the underlying code in english. It wouldn't even need any cooperation from language implementations or library developers, and it'd be compatible with all legacy code!
I'm not saying that it's a good idea, though, just a possibility.
Just as an editor can show → for -> and λ for \ if adequately configured, it can also show 'если' for 'if' and 'Функция' for 'function' (or, say, the chinese equivalents) while keeping the underlying code in english. It wouldn't even need any cooperation from language implementations or library developers, and it'd be compatible with all legacy code!
I'm not saying that it's a good idea, though, just a possibility.