I see, is that one foreigner full stop or just one foreigner per country and course max? I can see how 3 spaniards one course can cause trouble (since there would be plenty of opportunities to speak spanish) but having for example one german and one french on the same course shouldn't do a difference since their only common language is most likely english.
They would then speak the same language... €uropean!
yeah man, you're right. Only 1 foreigner per country in the same course, with no limit if coming from different countries where the first language is not the same or similar.