One thing I'm completely ignorant of is how to people from countries where non-latin alphabets are write code? Eg if you're Chinese, Arabic even Russian do you have to do everything in English and English characters? I'd hope there is a Unicode mapping into other characters - is there any language that supports this? Even for libraries would be nice.
Russian reporting in. I think everyone here who writes code knows Latin alphabet. It's just a basic requirement - it's a given that if you want to code you'd better learn English, let alone alphabet. In schools, kids learn to code using Algol-like language with identifiers in Cyrillic (essentially, Russian) abbreviations, e.g. "нц для i от 1 до n" rather than "for i := 1 until n do", but even here you see Latin lette…
There was (is still?) a project to translate all the German comments in Open/Libre Office into English, a legacy of the German company that originally wrote it.