Most expats I know here have done well, sometimes 5+ years, without ever properly learning German. So language is not an issue. That said, you do need help whe

Most expats I know here have done well, sometimes 5+ years, without ever properly learning German. So language is not an issue. That said, you do need help when dealing with the bureaucracy. It can be complicated, and they often do not speak English. But it's trivial to get this help from colleagues or expats. 90% of those I work with are German, and yet I can get by speaking only English as 1) they will switch to English, like I suspect most German developers can and would, and 2) our CTO and a few others in the office are not German either.