While I could be fun and read too much into nonsense, I'll instead be a curmudgeon:

I think it's a bit rude to submit a non-story to a contest where lots of people are trying very hard to write a good one.

The narrator enters science heaven. And then what?

The majority of the text is explaining how science heaven works, which is fascinating, but it seems to be missing an actual story.

I liked this a lot. It felt like a fable. Short, simple, and to the point. We thought the lesson was for Petunia, but the real lesson was for the adults.

As an aside, I was half expecting the Twilight scene to end with:

“So what you’re saying is that if I could come up with the time, we could go?”

“...Maybe?”

Cue Petunia going to Doctor Whooves / Starlight Glimmer for a time machine.

But perhaps that's too silly for what is a very sweet story.

I think >>Not_A_Hat is right about the emphasis. Bold text is powerful and seems excessive where used here.

Celestia's reticence seems out of place. She's already chosen Twilight to be her protege, so Twilight should be among her top priorities. She would need a good reason to justify not being able to attend, and if she had such a reason would she not tell Velvet that outright?

The core of this story seems to be Velvet's concern that her daughter doesn't have any friends, and her subtly trying to push her in directions such that she makes them.

If Twilight's problem is no friends showing up to her party, then how does Celestia and twelve burly guards showing up solve it?

The conflict is within Velvet, because Twilight is perfectly content to be a bookworm at this point. She doesn't know that she needs friends. Given that canon Twilight doesn't learn this for a while longer, Velvet must fail to teach her that here. So I suppose it makes sense that her plan isn't very sensible.

But I think it'd be better if she had a sensible plan that failed, rather than a strange one that works, because then Velvet understands what her daughter needs but not how to get it for her, and to me that's a more compelling story.

I think Twilight needs to take some lessons from Iron Will!

And Cadance needs to take some lessons in communicating.

I was really into this up until the end, and maybe that's because I need to learn the lesson being taught here, but Twilight is being a total pushover. What does she get out of the deal? Twilight letting foreign officials push her around like can't be good politics. Would her acquiescence not just embolden them to push for more from her? Especially because they now live with her! She's solved today's problem but created more in future.

It doesn't help that the summit's conclusion was glossed over. All that build up and you skip the grand finale?

Opening with self-deprecating humour and meta-commentary anchored me into thinking this was a goofy randumb story, but it turned out to be very serious and ended up with everyone dying in a tragic accident or killing themselves in grief. It made an already confusing experience even more so.

I think this story is very unfair to the reader. I spent most of the time trying to find my footing, only to have the rug torn out from under me every time I thought I'd found it. And I felt like the author was laughing at me, like I was a fool for even trying. The final meta-commentary in particular left a very bad taste in my mouth. Predicting criticisms doesn't make them less true.

The interesting story here to me is the relationship between Berry Punch and her daughter, and it could have been told without all the tomfoolery.

Why are the human characters using pony terminology?

>>JudgeDeadd
I don't think it's terribly unbelievable. While it's an obvious explanation, it's orthogonal to the question, "How did this spell get cast?" which Celestia spent all her efforts in answering. She got trapped down the rabbit hole of the wrong solution space.

At the very least, I didn't predict the explanation.

>>Zaid Val'Roa
The author wrapped the lines to 80 characters. I only noticed half way through, but as soon as I did it became pretty distracting.

I think the twist pigeon-holed this story into glossing over a lot of interesting things that could have explored, namely how the negotiations went and how all the ponies of Equestria reacted.

I admit the twist was quite a shock, but mostly in a sense of relief that I wouldn't be reading any more about a messy war. I'm not the best at visualising things, and the entire war sequence left me quite dizzy.

The concluding banter between Celestia and the military men was much more comfortable. The way the soldiers talked seemed very on point and funny in a boisterous way. Notably, the exchange between Celestia and the medic gave me Catch-22 vibes.

The mystique of this story lust its lustre as soon as this being a San Junipero crossover became clear. The drip-fed exposition and elaborate descriptions then became less intriguing and more exhausting.

I feel similarly about this as I do So Be Prepared to Precede Me. Only this time, twice as many words were spent describing science heaven.

This was very lovely, and the bits of comic relief sprinkled about helped cushion the blow of an otherwise tragic story.