Unless they're titan shifters they should not be shifting back and forth. Plus if they can go back to their former appearance then why did they waste over 30 years hiding? This should apply to the fnaf gang too but this ability of shifting human to robot is only exclusive to the Aftons. Which to me seems like a huge middle finger to the murdered kids. I'm highly positive if someone literally shifted into a robot screaming/ or killed someone in a public area the police/swat,CIA, team would be hunting them down.
Plus the fact they even wait that long but yet are the same ages they died I'm pretty sure it would mess with their birth certificate. Plus the fact that it also has been thirty years how are they still owning the same house? Like during that duration someone else could've purchased the house upon them being gone.
Then again they will all team and kill those they deem in their way. How do they even have money, and they're going to be pretty outdated when you think about it? Do they even need the house anymore when they and other animontronics make their home in wherever they're at?