It's not about the language, it's about the culture, Djokovic is the same. And i don't think he doesn't understand what is right to say and what isn't. If you understand the language you know what is appropriate and what isn't.
I really don't understand What you two mean.
give an example of a controversial statement that Roger Has made and can be blamed on lack of culture or knowledge on how to use the language?
As for Nole, the stuff he says in English that makes GM implode, my opinion is that he would have said the exact same thing in Serbian.