The controllers that are provided with RealFlight for the WS2000 are called "Spektrum Receiver". That's the device that's connected to the computer, so that's what RealFlight is looking for. It doesn't know what kind of radio you have bound to the receiver, and honestly, it doesn't matter. Instead, it's more important how you have configured the model in your NX8 and which channels are assigned to which switches on the NX8.
You'll definitely want to refer to the two pages I linked in my previous post for more info.