Such a dumb situation, and I really appreciate you trying to sort it out.
I had an issue with a neighbor with substance abuse & mental health issues. He would yell all day & the majority became directed at me (I told him to stay off my property when he mowed my yard/garden- so clearly I was the reason his life was shit.) The entire neighborhood stopped going outside to avoid him, and a few people moved. The police were involved several times. Unfortunately by law, unless he threatened someone, or actually came on the property again, he was in his rights. Doesn't sound like the offenders are anything but frustrated with noise, and are being creative, yet kinda assholes in their mode of venting.