This is my Chinese teacher, his name is Josh. He is Chinese. My good friends name is Cindy. She is not Chinese. Her mum is Chinese, her dad is Japanese. I am John's student. 我们是John的学生  （这里室“我们”不是“我”）

This is my Chinese teacher, his name is John. He's Chinese. My good friend is called Cindy. She's not Chinese. Her mum is Chinese and her dad is Japanese. We're John's students.

This is my Chinese teacher, his name is John. He is Chinese. My girlfriend's name is Cindy. She is not Chinese. Her mother is Chinese, her father is Japanese. We are John's students.

All are correct 

This is my chinese teacher, he is called John. He is Chinese. My good friend is called Cindy. She is not Chinese. Her mother is chinese, her father is Japanese. We are John's students.

correct