I am not sure about日文老師 because my son never speaks any Japanese at home. BTW, the time for 國語和日文的老師 is only 15 mins per week? Parent can never know what 國語和日文 their kid had learnt as nothing is mentioned in the student handbook.
I just want to share my experience. Yes, some people are lucky to have good class teachers. If you pick Ming Wai, you are taking the risk. You may need to quit at the middle of the term like me. It is not only difficult to find another school, it may be a nightmare for you kid.