This is incorrect. As an Aussie I will freely admit to saying ‘crikey’ BUT no one has ever said ‘donga’ in my hearing, and ‘cunt’ is such a common word that it should probably go around the middle. I mean, we use it as a term of affection for crikey’s sake.
As an American, I’ve never heard many people say twat. I have heard a lot more people say fuck than twat, so maybe it should trade spots. Then again, you can probably say twat multiple times and keep a PG-13 rating in a movie, but if you say fuck more than once (or sometimes twice), you will end up with an R rating. Maybe twat is more acceptable than shit, since saying shit once almost always requires a program to be on cable/satellite (for TV14) OR to be rated MA if it is on any channel that is easier for children to access (like CBS, ABC, etc.). Now, the word tits on the other hand would probably be more offensive than twat on American television and in American movies.