Helicon1 Psy. profiling was given up at Maastricht a couple of years ago as it didn't really work.
The working language at Maastricht is, of course, English. French, German and Dutch useful for co-ordination and of course in your daily life. It would not be fair to give one group any advantage by producing documentation more easily assimilated by them than by say, a Portugese.
Some general advice;
Think about the ICAO "definitions" of ATC; Why do you want to become a Controller in Europe; What is Eurocontrol and why was it created; Is castration a suitable punishment for spotters.
Be prepared for anything, if time permits before your interview it wouldn't do any harm to ask if it would be possible to visit the Ops. Room- beware of wind ups however.
The best advise is to be yourself, be honest rather than bull**** if you don't know an answer.
Good Luck to all of you