I have looked at how Edge Animate does it. But would actually prefer something else?
Since spritesheets really are only an animated movie or image sequence right next to each other in the same image, then later to be moved by Hype an amount specified per frame... It would be much greater to have a converter.
Say, you import an SVG or PNG or GIF or JPG sequence, Hype converts it into ONE image and then the user only have to give the frame per second. Width and height is specified already from the image sequence.
Then with a script in Hype, it would just move the image by X pixels per specified by user FPS. Get it?
Maybe it would be troublesome to make ONE image out of a sequence, but this way you could really make a spritesheet out from any software. Flash can export SVG sequences already and After Effects can make PNG sequences.
If the image later is available, then free compression softwares like ImageAlpha, ImageOptim and svgo-gui could be used on it.