No idea but for my PGCE interview I had to write a text in English (theme was free, aim was to show good use of English and punctuation), and non-native speakers had to do a translation task into their main FL, to show how good a grasp of their language they had, I guess. Subject knowledge could be as simple as "can you speak the language accurately"? When I interviewed recently for a post of French teacher at my place I had an informal discussion in French with candidates, as well as asking them to mark an A-level essay, simply to check that their level of French was good enough for A-level teaching. Don't panic! Well done for getting to the interview level!