I can't speak to what program would be best to animate the bars.
As far as displaying the animations in C2, I agree with newt that it gets tricky without an option to animate tiled background. You could create different tiled backgrounds for each frame, and create your own animation system using events, but that solution is pretty ugly. Another option would be to do something like this:
I'm using a sprite for the bar's animations, and a masking sprite on top of it. Changing the width of the masking sprite makes it appear as if the animated bar is growing. It's also kind of ugly, but it may work for you.