It might depend on what grade my child was (we have the same music teachers all three years of MS), but honestly, I would re-send - not through portal if you can- and copy principal and county orchestra. I would say that I am concerned because you aren't sure who is supposed to be in charge of this at your son's school and you are not getting any response to your emails. I would add that you were very surprised to learn of these scholarships - AT the concert! Both my sons are in orchestra in MS (luckily I love the teachers) and there isn't really a lot a teacher could do to retaliate in our school. Not to mention, if that is the worst parent email they get, I'd be surprised! Now that my dd is a teacher, I realize that if I'm not swearing and screaming at teachers, I'm not the worst. And she (dd) usually just feels bad for the student if they have that kind of parent. It doesn't make her angry at the student.
So, I'd call them on it. I hate to say, but I think you're right and it's probably too late for this year, but maybe it won't happen again next year!