Well native speakers would not have a problem, you wouldn't survive even the PPL ground school if you have don't have a basic understanding of English. However, in terms of the cadets, a good percentage of them are not native English speakers (like myself but I haven't applied yet).
Now my question is does every cadet need to take that English course once they start the cadet training.
PS: I don't think you will ever run into a pilot from an English speaking country that don't speak fluent English. May sound different but this is an industry with a standardized language.