*glances at the brand new Potter land under construction at Epic Universe* I wouldn't worry about the rights lol.
I have no inside information on how the rights to those properties work at all, but it's kinda always felt like the rights to Saw were thrown to basically anyone who asked for them and were incredibly easy to get. In 2008, there was an official haunted house for the property in a random California shopping plaza. 2009 had a haunted attraction at Thorpe Park, Universal Orlando, Universal Hollywood, and Fright Dome Las Vegas. 2010 had it at Warner Bros Movie World in Australia. Then, it came back to HHN in 2017. And so on.