Why use name of particular hairstyle 堕云髻 （low cloud bun？
The translator is being too clever. He forgot that there is no reason that Miss Bürstner would wear an ancient Chinese hairstyle. The word 堕云髻 is misused here. 

It might be that the translator subconsciously wanted to show off his knowledge about hairstyles, which obviously have failed. 

This translation is done by 曹庸, one of the best translators from the past generation. Translation is hard work. It shouldn't be surprising to see even the best translators make mistakes.