Bringing foreign language cartoons to America requires more than just a simple translation. Fans don't want to watch a show that sounds like something from Google translate.
Plus, the animation itself doesn't change when it's brought to the U.S. Just the script. So the timing of the English dialogue must be consistent with the original cartoon. That's not easy. Something that takes 5 seconds to say in Japanese might only take two seconds in English. Unless the script is fleshed out, a character's mouth will still be moving long after he's finished speaking. Working as a script adaptation writer, I fix these problems while staying true to a show's original story and creative vision.