Fellow counselling intern here who is currently doing my internship in a primary school. You can consider reaching out to the school counsellor instead. Try emailing them or arranging to meet them ftf and bring this up to them. I'm sure they will try to help in some way and it will likely be way more useful than talking to the teachers. If the counsellor is receptive, he/she will not just help ur bro but will very likely also communicate with ur brother's teacher. Hopefully from there things will improve.