Maybe so...I'll admit that when I heard she would be "getting her own house" I assumed they would just film in a part of the mansion that we haven't seen yet, or (like you said) they would just re-dress some rooms of the mansion to look different. There would be an establishing shot of some Atlanta house to let us know where the scene is set. Which is fine with me, because it saves money for things that really matter.
When Fallon told Liam that sob story about having peeked in the windows of the Winslow house as a teenager, enjoying watching a 'normal' family eat dinner, play charades, etc. I fully expected Liam to say something like "You expect me to believe that?" since it sounded so ridiculous, the sort of lie she'd make up just to con people into going along with her latest hare-brained scheme. It's still ridiculous, even if they want us to believe it happened.