Yeah its good they have teeth in Uboat,
As well as NPC submarines, destroyers and planes will probably get torps too eventually, though they rarely deployed them against U-boats IRL - opting for cheaper and less risky weapons in their arsenal.
Honestly though a torpedo or mine hit shouldn't just cause a bunch of hard to recover from leaks, it should really be a death sentence.
A torpedo hit would snap a Uboat like a twig. Mines were usually fatal too, though there was that one Royal Navy T-class submarine that somehow limped back home across the north sea with out its Bow. Apparently one of the ratings asleep in the forward compartment had to be woken up by another crew member, he didn't stir from the huge blast, must have been very tired.
I guess in that case the crew reacted quickly enough to evacuate and seal off the forward compartment before the whole boat flooded.