This sounds horrible and I'm sorry for what's happened to your family. When you say Roblox _seems_ to have controls, do you mean that disabling chat doesn't actually work? Because I've tried to lock my kids accounts down as much as possible and had convinced myself it was mostly harmless.
It was two years ago, so maybe things have changed a bit. I don't think the game works well without the in-game chat stream. If that can be disabled then perhaps some of the risk is gone. It is still a creepy place with a lot of 'dating' in the game. My daughter was also introduced to the concept of a furry very young. She though it was more innocent than it actually was.
Roblox is disabled on the firewall. It will never be accessed again. She still plays games that are fairly locked down on xbox, and I trust the parental controls of Microsoft more than Roblox. I also put in a gryphon router to help take some of the load of us, as parents, policing everything.
