It honestly sounds like you have tried everything! When I am outside with the kids I am hyper aware that their noises are bothering the neighbours but my group is not loud at all unless I have started a new baby who is not used to being outside, but that typically lasts a week or so. It is not my contention that kids are supposed to be loud. If they are actively engaged in activities it’s not loud at all.
I think the only option is to go somewhere else to work OR move. It really sucks
