I agree with you. Ignoring the occasional inappropriate word or phrase, I think that this is a mature piece of work.
Even if there were no inappropriate words or phrases, I would not believe that this had been written by a British or American student, but that is not because of any Chinglish. People from different cultures express ideas in different ways. So, I feel that that if this is not fully 'idiomatic English', this is not because of mistakes as such, but because of the thought processes.
If the student has lived in China all her/his life, then s/he has a very sound command of English indeed. If a student of mine produced a piece of work like that, I would be very happy.