@Cinebar you don't need to rebuild any lots.
Any house can be a haunted house, even pre-built lots already in your game. The trait is also not tied to any world, meaning these specters can go anywhere you desire. All you need to do is enter build mode and change the lot type to Haunted House Residential. Just make sure you've selected the Haunted House lot type, rather than the Spooky lot trait which simply encourages more ghosts to hang around.
Haunted houses can be a great place to live, especially since you gain reward points for each night you get through. However, they come with a few unique traits that you need to be aware of and understand. Here's everything you need to know about the new Haunted House Residential lot type
The Sims 4 Paranormal Stuff: Everything You Need To Know About Haunted Houses
https://www.google.com/amp/s/www.thegamer.com/the-sims-4-paranormal-stuff-haunted-house-guide/amp/