I think it depends on what you're working on. I often find myself having to use legal terms for which there are no direct translations (because they do not exis

I think it depends on what you're working on. I often find myself having to use legal terms for which there are no direct translations (because they do not exist in English-speaking countries), or there are analogous terms, but they do not mean exactly the same thing, or are very awkward to use (for example, a common abbreviation which everyone recognizes at once becomes something incomprehensible after translating it to English). So we can either use Russian for comments and git commits, or spend a bunch of time digging though specialized dictionaries and force everyone getting acquainted with the code base to do the same.