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 letter "i" ;) However, it's not uncommon to just go with e.g. BASIC or Pascal.
There is also de-facto standard accounting & ERP software producs from 1C which use Visual Basic-like language with Russian identifiers like "Константа" for "Const", etc. It's widespread in its domain, but not used anywhere else. 1C programmers are sometimes (half-jokingly) considered to be of a different caste. Sort of like COBOL programmers, maybe, or - probably closer - SAP developers.
I don't think anyone has any serious issues with basic English language for identifiers. Literature, documentation, discussion - here, language barriers do matter (a lot!), but not for programming languages themselves. That is, unless someone wants to show off as a true hardcore Russophile, of course.
Code comments, identifier names and e.g. log messages are different matter. I don't think there is any common practice for this - more like a matter of personal preferences. Some try to stick with English, some use Russian or transliterated Russian (mixing it with some English) liberally so it's not uncommon to see something like `log.Error("Дом не найден %s, %s: %s", ulica, nomerDoma, responseText) /* TODO: Добавить поиск лучшего совпадения */` in their code.