Sonar ignoramus here.

Can't you get the bearing and range with passive listening from two points, and/or single point but measuring over time?

As for why not to confirm a solution with active sonar before firing; if what you described are rules of the game, then IDK because it doesn't seem to load anymore. In real life, I imagine an active sonar ping being much clearer and more informative to the enemy than the noise generated by launching a torpedo.