Do we have zoning? I'm a R6B zone. It won't divert water onto my property. The fence will keep it on his side. The biggest effect of his fill is the silver maple won't like have the soil level raised above much of its roots.
The fence over height is simple. I call 311 and the building inspector comes and measures. The only way to reach him is snail mail or walk around the block and ring the door bell. But as I have noted elsewhere, it is the contractor and architect that did this.
Don.