Hmm... if the footstep fireworks were actually done, I hope we'll hear it soon. But I could imagine some 'home camera' footage being CG'd, too, to add to the illusion.

As for the complaining about a different actress being used for the singing... again, people acting like this was an evil commie plot rather than a simple part of performing arts. Yeah, they chose a performer who looked the part, while using the voice talents of someone who could sing well. It was all about putting on the right show. If you could interview all the performers dressed in cultural minority garb, you'd probably find that some of them aren't actually members of that particular minority.
When Jack sings in The Nightmare Before Christmas, it's not Chris Sarandon, his voice actor, but a substitute. Same when Yuna's singing in FFX-2. Should those actors have got into a huff because their talents weren't considered good enough?

The girl who actually sang at the games had her voice heard and appreciated by countless millions of people. That's pretty cool in its own right, especially for a seven year old.
I wonder if anybody snuck anything in that tells the Chinese people about Tiananmen Square.
There were a butt-ton of protests at and around the Square in the leadup to the games, so plenty of people do indeed know - even though it's basically a forbidden topic in the Chinese media, except for the one-sided representation which tells of the military having to respond to mob violence and vandalism by a rampaging horde of protesters.

I'm surprised at just how widespread the view is, that everyone who lives and works in a communist country is a one-sided and one-dimensional evil-doer, like a villain from a Cold War comic book. The reality's a lot more complex than you'd think.