Edit:
Mainly tweaked the colors. Heightened contrast and saturation. Some other color and design ideas and tweaks. I don't know if you were going for pastel colors, but it looked washed out. Unless they are supposed to be a ballerina, I'm guessing they should be more solid on the ground. I also messed around with the lighting a bit, but that isn't necessarily the best, just something to think more about.

started with animating the typewriter, maybe it needs to be fastened to 200% if it actually writes the letters out (but it's already down to 20ms/frame ...)

Cels:
already edited the water and various other stuff - same goes for the char's shadows (since they are so short now it works, otherwise this causes clipping issues with layers if you are running next to a wall)

This feels like a better speed, maybe even snappier, especially if you are going to have it type something out. The elastic effect also looks really bad, imo. Its seems typewriters aren't designed for motion like that. Here is an example I searched up quick;http://footage.shutterstock.com/clip-113290-stock-footage-close-up-of-a-vintage-typewriter-with-the-words-p-s-i-love-you-native-audio-included.html. The real life examples I've looked at seem almost instantaneous, but I'm not that familiar with animation to tell you how fast or how many frames to make it. Don't forget that not all letters come from the center, too, there will be a slight offset!

I'm no typewriter engineer, but this is what I take from my observations.

I don't mean to drag this out into a new AA thread, but I whipped an example up. I'm sure what I'm going to say has been said before, but its been on my mind, so I'll let it out.

I find it interesting how the different contrast levels affect aa. in A with 100% contrast, aa is definitely needed. I also had  to use two aa colors to make it look right. B, with 50% contrast, only needed 1 aa color. C, 25% contrast, there is no aa and it looks fine. Its interesting how contrast effects the need for aa.

Then all of a sudden, I thought how these rules apply to dithering. (Top is dither, bottom mixed color. In C, all are dither)

With A, there is no room to use 2 extra colors to aa between the black and white, so it looks bad. B looks okay. C it is hardly noticeable there is a dither pattern.

It's kind of like dithering is a type anti-alias arranged in a tight repeating pattern, if that makes sense. I'd also be interested to see if it would be possible to make a dither pattern involving more than two colors, maybe even 4, to further support this. I may edit this a bit, or make a new post, about what I'm thinking, but I think I need to go to bed soon to refresh my brain.
I feel like this is borderline gibberish to the more experienced artists here.

On the topic of this technique, I feel it should be fleshed out more as an idea. Maybe add more rules in support of single pixels.
Here are my ideas, but as an amateur, take them with a grain of salt:
Pixel art tries to push the boundaries of bitmap images. Sometimes there will be a "shape" that is too small to be more than one or two pixels or too big to be ignored. This picture is an attempt to show how a complex shape (below) may be portrayed in single pixels (above). Sometimes this may force us to use single pixels. Sometimes it may be better to change the form of the shape to make a better cluster with less single pixels.
Antialiasis shouldn't be explained as making an outline smoother, but as a way to better portray a shape/cluster.

I don't know how to explain dithering. Just my 2 cents here.