Bizdev I asked exactly the same thing on one of my SEP courses as I totally know what you mean here.
The answer given to me here was along the lines of
if you choose that carrier then it is assumed you understand the language of that carrier.
I'm not sure if that is the view of ICAO or of that individual trainer at the time.
I do know this is the legal position though.
My own
personal view is that english (however lazy we undoubtably are) is the official and universal language of aviation so we should all be delivering a brief in this language wherever our airline is registered as well as the native language of the countries concerned. To me that would be best practice.
I don't suppose ICAO care what LCD thinks though!