We know the residents of WestView are real since we've discovered that the town itself is a real location that S.W.O.R.D. has been watching. An obscene amount of Easter eggs suggest that several residents could be Marvel heroes and villains, and if they are, we have to wonder how they also wound up in WestView! There's a storyline in the comics where, after the Salem Witch Trials, Agatha Harkness and her coven shields themselves from mortals and call their community New Salem. I theorize that WestView used to be a haven for witches, and while Wanda was searching for a place to call home for some solace, she stumbled across the community before things went topsy turvy!
Whoever it is that's controlling Wanda could have trapped all the witches in what used to be their home and is using them as pawns while they sit back and watch. It could explain how all these potentially powerful people came to live be in the same prison. And we've seen that some people are seemingly aware that there is a world beyond their sitcom reality, which lends to the idea that they remember a time before Wanda and Vision lived among them. It would also explain why Agnes asks Vision if he and Wanda are there to save them in footage from the trailers.