My suggestion is that the hidden object mode will act as a treasure hunt like in Cooking Dash with missions related to unlocked venues and hidden object scenes you can buy with coins and gems, and the prize will be a new outfit/tickets/keys/auto level-up for characters etc. Every hidden object event will have a story with tasks that ask you to collect coins/hearts of characters to unlock testimonies/interviews etc as a way to explore the mystery. The hidden object scenes will uncover clues, which can be sent to the police station or somewhere else for analysis (which will take real time, or can be paid with coins or gems).
Elements from DinerTown Detective Agency can be brought back like finding a list of objects, finding pieces of equipment to solve puzzle (like collect a light bulb to light the scene, finding a key to unlock the locker ...), playing mini-games (assemble the clues), and finding out the guilty party based on the testimonies and interviews.
I hope that this suggestions will encourage us players to spend more time (or money) to play the game. Thanks for reading.