Hey Chazman89!
With each update the questlog will have what's available if you've reached the point in that particular update. (Our announcement posts usually let you know what's in the current patch too).
In terms of the scene/image gallery: Outside of hovering over and seeing what time of the day you need to be at to find certain items, in a particular room of the house, some of the unlocks require special conditions. We want this to be a fun way for players to explore the house in an item hunt type of extra game, in a way.
I would suggest searching each room, for each time of day. Some are well hidden and others can be tricky.
If you'd like, we have an awesome community on Discord that might be able to help out too!
Thanks a bunch for time/support with AHITR!