Question for your Cryptid AU, do Sun and Moon still hold that need to protect children like in the rest of the fandom? How is their behavior to kids different from their behavior towards teenagers or adults?
They love kids and would never harm one. Even if the parents treat the woods wrong. The youngs are innocent and always have potential to grow up to become better people.
They'll probably still give the adults a terrible scare to get them to leave the forest. In a few cases killed a few wrongdoing adults in the group if they were bad enough, but not enough that the kids would be left on their own with no guardians to leave with. Still a horror AU. Breaking the rules are paid in blood.
A child lost in the woods will find no danger fall upon them, they'll be kept safe and helped to find their way back to their family or nearest civilization. Some even return with stories of a friendly creature ensuring they had food and shelter depending on how long they would be stuck out in the wild.