Ok, bit of Fridge Horror here with Magical Mystery Cure. The Episode makes Star Swirl the Bearded into a kind of Tragic figure. I know they were going for a Fermat's Last Theorem thing but think about it - Star Swirl failed in his attempt to toy with destiny and there was no counter-spell to fix it which means that he probably messed up the destinies of his friends and never fixed it - ruining his friend's lives. Further since it works through the Elements of Harmony he was probably an Element Bearer himself and screwed up the destinies of the other five. This might have been the event that caused the three tribes to fall into disharmony so that the Wendigos could move in and destroy the old homeland.
In short Star Swirl may have ruined his friends lives and doomed his homeland by playing with Destiny.