As far as I know, Beixu Garden is indeed an illegal building, which happens to occupy the position of a road to be built. It is unclear how the two sides negotiated. However, it is recommended not to buy it. The house is not a small number, and there is no real estate license. Give you a little subsidy, and you will be forced to go. If you don't leave, you can't.
So forget it, look at other houses!