@throughstars
Its called using your brain and observing, you think the author is perfect? Everyone makes mistakes.
In the panel where her friend says "its so relaxing" the author showed you a scenery from her friend's point of view with no spirits, and the child with the balloon was in that scenery.
In the scenery where author shows mieruko's vision you see the same child and every other spirit.
Author fk'd up the consistency, just so he could create a stupid jump scare.
Also use your imagination? This is a manga they add visual elements to the LN, why would you have to use your imagination when the author creates a visual of his story for you?