Greetings! I'm one of the 3D artists in the game.
First of all, thank you for your comment, we are happy to receive feedback from those who play our game. You have to switch to camera mode because with that you can take photos of the objects listed on the list that appears at the top left of the screen (that's why they then disappear, because you took the photo of the right object) . As for the creepy character appearing in the photos, that should only happen if you took the photo of the wrong object.
Gotcha! That's why he kept showing up. Though there doesn't seem to be any penalty for shooting the wrong thing. I know a lot of games give you a little camera overlay when you are in camera mode and some highlight the UI in green if you are pointing at the correct object for instance. Adding that to the camera view would definitely make it easier to communicate to the player that they are pointing at an object of interest that you need to take a photo of.