Without knowing the exact situation it's hard to know whether the landing path is unsafe or not.
Many airfields have houses up to the boundary fence, I remember the first time I flew into Adelaide (passenger) being shocked at how low we approached over the rooftops. And that's 90 tons of metal, meat and fuel travelling at 135kn, not 600kg doing about 50.
As a father I can also understand your concerns about your kids safety.
You're doing the right thing by getting information. With forums like this you'll get some different views. What I can agree with others about is that good communication with your neighbour is the most important thing.
If you take a friendly approach, express interest in his aircraft from your engineering perspective, maybe he offers you a flight... then that's a good starting point to discuss your concerns. Maybe he can allay them, maybe you can work out a system where he lets you know his estimated arrival time so you and the kids can be out of the property while he lands... something like that.
One thing is for sure, if both parties get upset and angry - you because you think he's callously putting your kids at risk, him because he thinks you're selfishly stopping his hobby... then no one wins and it'll be hell living next door to each other.