Junoir Smith

The movie or series is indeed Great,the actions, bending movements etc ,but i have a problem for rating 3 stars, why and how did they get someone to play the role of kyoshie who even appeared in some of the scenes and they didn't get anyone to play the role of toph, how? I just don't get it. Even bumi had someone to play as him and toph who taught aang how to bend earth wasn't in the show(season 1) meanwhile this story is giving the reality of the animated last airbender