If you want to work by the rule you should do it all the way.
I do. And the rule states that I can use English
or the national language for ATC comm.
Well I'm spanish and I've got level 5 (can't get 6, since english is not my mother tongue).
andrijander, I believe that this is a (temporary?) restriction by your country's DGAC. English is not my mother tongue, yet I was given level 6 by the UK CAA.