Hello,
I have been wondering whether, if I write my essay in my native language (Bulgarian), this could backfire at the recruitment stage because the vast majority of officials would not speak Bulgarian. Could it be that they won't be able to get a direct impression of my writing and so be reluctant to offer me a position?
Other than that, I think it makes perfect sense to choose my mother tongue as L2 as the essay will test my active use of the language which is inevitably better than any foreign language.