Writing letters of reference for a faculty position in China?
Writing my comment as an answer, following a suggestion.

I’ve spent two years in China as a postdoc. I have never read a recommendation letter (LoR) but I’ve experienced the culture in academia. As someone else hinted I also do not think anybody will actually read the LoR in any detail, but just skim through it. The focus is on who wrote it (more precisely, what is the author's university ranking and impact factors). 
About the contents I’d recommend just dropping cliche positive comments but without any exaggeration. The Chinese are extremely sensitive to any form of criticism, and will generally not appreciate outspoken, frank discussions. This will look particularly "serious" if put in written, from a "leader" and addressed to 3rd parties, and might be interpreted as a gentle warning against the candidate.