::I can't see any problems using the term "Half-Jewish". Garry Kasparov uses it regularly refering to his own ethnicity. See for example the transcript for a radio interview made by ABC News (Australia) April 3, 2005. Interviewer Monica Attard comments about his non Russian roots: 
 ::- Attard: Well you were born in Azerbaijan as I understand it. 
 ::- Kasparov: Yes I am born in Baku and I am half Armenian-half Jewish but my native tongue is Russian, my culture is Russian, my education is Russian… (http://www.abc.net.au/sundayprofile/stories/s1335618.htm)