The biggest take away and clue from this interview was this
It’s not really a big secret that 21 of the pages reveal 21 locations in my town. The trick is to work out how they reveal the eventual location of the treasure. I can’t say too much more for obvious reasons! The clue pages are images with border text, its a classic armchair hunt format. It’s not giving too much away to say that some imagery and text is more important than the rest, but working out which bits matter and how they fit together is all part of the game.