What part of their actions could possibly have broken the plexiglass? It’s soup.

If the plexiglass was really low quality, and the can holding the soup was particularly heavy and sturdy, it's imaginable that the glass could have cracked under impact and soup would have leaked through to the actual painting.

Even a higher grade plexiglass could be easily scratched if the can had slipped - this wouldn't have damaged the painting, but would have required the plexiglass cover to be replaced to see the unblemished artwork.

And - this is just about damages to the artwork, whereas I already pointed out causes for other damages (cleanup fees, public disturbance). This is something that you pointedly ignored. Let's assume for the sake of argument that damage to the artwork is absolutely impossible. What about these other things?

but it was just never in the cards to begin with.

I will quote myself.

That's exactly what I said!

But then...

You’re acting like they took a risk and luckily nothing bad happened,

No, that's the exact opposite of what I said.

I'll quote myself again,

but also worth noting that it seems obvious that they knew there would have been no damage since it's pretty obvious it was behind plexiglass

One last thing,

A lack of intent isn’t what made this not an “almost ruin”, it’s that there is no likely outcome where the painting is damaged.

On reflection, I have decided to adopt your view as my own. You didn't bring this up, but the constellation of super minor and nitpicky "related damages" has no bearing on whether the painting itself was damaged or not.

And (you also didn't raise this point, but) even if the plexiglass was of such a low quality that a soup can hitting it could have damaged the painting, then so would a person holding a stout umbrella who tripped and fell on the painting - so then that's really negligence on behalf of the institution hosting the painting for not protecting it properly from accidents.