well, balance is much about tori knowledge.
it means that u have to know, how u have to move to counter that u fall to the side. which means u move the needed joints just a little bit to make it correctly.
as example i use rl. if u fall back, what u do to stay? u make one foot behind you. so u got balance to the back. do the same in toribash if u fall back - just move one foot a bit to void falling. well. now u got front and back balance, but now the possibility is high to fall to the side - escpially to back left and front right. (if u made the right foot behind you) to counter that u use the arms. just move them in the other direction youre falling, but not too fast so u dont get moved out of the pose by the momentum which u made with swingin the arm.
ill made a short and probably not so good example replay, but may it helps to take a look.