Max,
I agree with several folks. You said you would pull them if they were identified. The only logical response is to do so unless you suspect the songs are not copyrighted. My guess is that they all are.
And sure, HFA reserves the right to review further, lawyers always try to cover all of the bases. I think the fact that they have indicated only 16 out of the 8,000+ is proof enough that you did not intend to infringe on copyrights and in that way you have some legal protection.
I am sorry to see any song go, but the law is the law.
Roger in Baltimore