If the ashcan didn't fit your needs then the full version probably won't either.
How you build the mystery is something that hasn't changed between versions. The biggest addition to that was the TPG Clue Chart where it can help you create clues that don't necessarily make sense out the gate but can be interesting as you play.
There's an essay on ACAB. There's suggestions on how to play collaboratively better with some tools and conversations... it's got a better section on RPG safety and we added another layer of mystery but if how the mysteries were created weren't your jam then this probably won't be either.