Some people seem to forget that the elves led a rebellion against her . considering what would have happened in medieval times compared to what Celene did her response is mild not to mention she at first tried to calm the situation by killing the noble that was responsible for the mistreatment of the elves. Gaspard forced her hand however and she was forced to choose between 2 bad choices.
Even with all the backstabbing in the game Celene is intend to create peace between nations Gaspard , while a honourable bad ass will likely start a war between Fereldan or Nevera
A war with Nevarra is given if Celene wins - if I remember correctly it is stated within the first third. It is a bid harder to say what will
happen when Gaspard wins, will he invade Ferelden or Nevarra? Since I seriously doubt he thinks he can do both at once.
A lot of people seem to forget that Celene is no pacifist, if going to war suits her, she WILL do so.
But this point is kinda lost thanks to Inquisition, since Orlais seems to be the primary setting.
I mean, the breaches PLUS two simultaneous civil wars with the top of the chantry dead? Even if you end
the crisis, Orlais will be severely weakened after that, thus no war plan is going to happen anytime soon.