I was starting a short story - which should actually be pretty short - but I came across an issue. I am hoping for this story to be a period piece, meaning it is about a certain period in time. So, I've decided to write about Nazi Germany, specifically Kristallnacht. Anyway, since my character is Jewish, I am planning on using sparse Yiddush words for certain descriptions since I feel that they are better suited than an English version of the same word. I am also planning on writing a prayer in Hebrew in there. Is that frowned upon? Should I stick to English since the short story is aimed at an English speaking audience? Or is it acceptable to use words in other languages on occasion without defining them?