I tried entering some Chinese characters into the body of an ELU question, and it said
Body cannot contain (Chinese character).
Even putting it inside backticks or blockquotes doesn't seem to help.
In case it matters, the characters involved were from the Japanese title for Somewhere Street (I can't enter the characters even in meta).
While I understand questions and answers should be written in English, I think it should be ok to quote or discuss phrases in other languages (though it isn't vital for the question I'm writing).
There's a ban on Chinese characters because of spam, but I think there should be an exception for ELU, just like there are for other sites about language.