enigmatic puzzle - Who can spot the difference?

My family and I have just moved house! Lucky us!

So what did my family do? We held a housewarming party, and rung everyone in the neighbourhood up to invite them.

So, anyway, people were coming in while we were in the middle of conversations, so we decided to leave the front door open.

Then along came an old man (who I later found out lived next door), tapping his walking stick everywhere and causing a big fuss. That wasn't the worst of it! He brought in a lot of sticks from outside into our living room, and knocked everything around that we'd unpacked. After a while, a little kid said, "Grandpa, I think it's time to go home."

But it was already too late – have a look at the trail of destruction he'd unleashed! Look at the marbles that had gone everywhere! The blocks, the balls, my Puzzling notes! An abacus, a calculator, the matchstick puzzle I was working on! You get the point! Previously, everything was in a neat pile! I'm surprised he didn't knock the whole bookshelf down!

Now some stuff's gone missing, though surprisingly some things that we thought were missing have been found. Still, I've got a good mind to give this grandfather a stern talking to. But before I do, I'd like to ask for a second opinion, in case there's something I've missed. Is there a reason for me to keep my temper?

Oh, and here's a picture of the damage, so you can make an unbiased decision:

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(Hereon is not part of the puzzle, just some random notes)

Thanks to TheGreatEscaper for helping to test-solve part of the puzzle!

For those who still appreciate the art of freehand circles, this puzzle (apart from the post text) was made completely in MS Paint.

If this appears in the LQP queue for a subjective title, please don't change it! It's part of the puzzle...

There's also a smidgen of reverse-puzzling involved.

Unconventional Tag Fusion alert!

^{This story is based on a fictional event and taken from there...}

Part of an upcoming metapuzzle.

Answer

If you click the image to see the damage, you notice:

it leads to a different image! Taking all the differences between these two images gives:

which looks suspiciously like a Slitherlink puzzle.

However,

if you try to solve it, you run into a problem.

Er, several problems. There are a ton of ambiguities there!

So let's take a closer look at those:

They're all aligned on a grid, which suggests that we only look at the locations of the ambiguities.
The reference to the man not being able to see well (needing a walking stick), and the first letters of the titles of the books all suggest Braille.

Marking all those locations gives:

which spells HE IS BLIND in Braille.