Woah, I'm surprised you found all of that!
There is one more hidden place to find, where the four stones are to be used...
Does the replenishing of stats/increase of one of the stats after touching the idol serve any functional purpose or is it merely a secret that changes nothing? Also, there may be a bug as I was unable to read the moon scroll while the star scroll was also in my inventory. I had to replay and only get the moon scroll to be able to read it.
The stat change doesn't have any real meaning to the gameplay, it's just some narrative flavor, and the closest thing to a "reward" that I can provide in this game.
The issue with the scroll is actually somewhere else, as it should only be possible to obtain just one. It comes from the Briar Seed item not being consumed when given to the campfire NPC.
I just released an update to the game. In the update I released today, I actually solved that problem. The Briar Seed item is now consumed when given. If you are still somehow able to possess both scrolls, the event will now alternate between the ones you read.
As a side note, I'm shocked anyone actually made it there, or noticed the other details! Nice job, my friend.