there is an opinion within the EU that you are not allowed to libel it

Correct, if the 'you' in that sentence is explicitely and solely read as a person on the payroll of the EU. Members of the general public are not meant by that 'you'. So, unless the EU is your employer, Bald Eagle, you may safely call it 'corrupt' and other words. If you happen to have an employer try to imagine how they would react if you'd call them e.g. 'corrupt' in public while mentioning your position as an employee.

Wolfgang