Don't worry mate.
You can disregard that statement by your employer. (Which airline is it?) In Europe you may speak any language you would like. For all normal day-to-day communications between people there are no restrictions. The only language restrictions that an employer can dictate are all technical communications, these must be in English.
- checklist reading
- flying the airplane (set speed two five zero/ gear down/start right engine/ etc)
- AML entries must be in english
- the like.....
but small talk at FL350 about the color of the underwear you are wearing may be done in Cherokee if you like.
