I feel this is the scenario if they were lost. They likely would have sought shelter/refuge, succumbed to the cold/elements being so small.
I believe a child would make a makeshift type "fort" from tree base or dugout, leaves, branches, etc. I see my kids do these things when we're in nature or at the beach (logs washed up, rocks, etc). They will make stuff with what's around them.
Children can be crafty and imaginative, so I wouldn't be surprised if lost, these children will be very hard to find.