Very cool, if true

It's tempting to say that the difficult part is conveying the right emphasis and emotions, rather than just pronouncing all the words intelligibly. A human actor voicing a cartoon character has to function as an actor, after all, not just someone reading out a script any old way.

But even there, the video side is much easier than the audio side, because cartoon artists have no difficulty producing line-art facial expressions from which we can interpret emotions.