TLoF means that environmental hazards really aren't for us. CCC means that we will be able to escape. In fact if we are helping our friends escape from a environmental hazard they both apply at which point Molly is a transcendent genius at everything.
So the big risk is we don't get as much loot.
Molly personally would be protected from environmental hazards. Others would not, and even a 3 DC modifier might not be enough. Even a 6 DC modifier (with CCC factored in) might not be enough.
There's also context, which is important. From description, the person we have contact information on is a mundane young adult. How did they get the information? A number of scenarios present themselves:
1) The well is accessible somehow, and he was inside at some point. Maybe he's the only survivor of such, and the others might still be trapped inside. If so, we might want to rescue them.
2) He's not actually a human but a changeling / alien invader from the almost-universe. Which would mean that it's inhabited by sophonts or close enough for government work (unless they are raksha)
3) He's the last in a long line of some sort of secret holders. In which case we want to know the secret.
Basically, while I am reasonably certain we and our companions would be able to get outside alive, if we are to profit from this endeavor, we should gather intel first.