“If nobody is looking at a mirror, is it reflecting anything? Or is it blank until someone looks at it? “
It is never blank. It always reflects what is in front of it. Whether a human sees the image or not is irrelevant.
This is a scientific fact and does not relate at all to the (pseudo)philosophical discussion above.
I have often tried to determine what exactly happened to the child in this haftarah. I have not been successful.