Obviously, it is not necessary to learn all those languages. What I really mean is that the problem is that sometimes you speak to Spanish/French/Italian-ATCs as if they were friends or relatives of you -English native speakers used to a colloquial register-.
That's why I asked you to imagine yourselves working every day in a language other than your mother tongue (English in this case). Maybe things would be better if you tried to speak slower and more clearly: like Queen Elizabeth
(some kind of "unaccented" English, that is to say, RP English (Received Pronunciation)-. All in all, you are talking to people who are not English native speakers.
Cheers
