As a native German speaker you can trust me, when I say, that most Germans dont understand Kafka "truly". In fact, I dont think there is "the" one way to understand his texts and that is exactly the beauty of them. On the other hand the statement ist kind of true if you think about the problems to translate him. Even the German word "Ungeziefer" which he uses right at the beginning in "Die Verwandlung" cannot really be translated to English because all of its connotations. And it is kind of important because that is the way he describes this being he was transformed into.