In C, Java, Python?
Literally nothing at Google except third-party code (like Linux kernel) is written in straight C. C++ is very common, though.
Python sucks and is useless. Most things that were written in python are now written with Go.
I guess your question is about what happens if a C++ expert ends up on a Java team, but I don't really know. I happen to have landed in C++ world, which suited me.
This is simply not true in any way.
The reason Python tends to suck is not all really nice libraries are ported to it in any reasonable amount of time. (If you need it, you end up doing the work). Go sucks in new and totally different ways.