The issues with the Mark-14 were being fixed by that time, but the Mark-13 and Mark-15 were never fully debugged. Not the first time that those going into combat have had to deal with weapons that didn't work, but imposed upon them by politically connected weapons makers. The contrast between the U.S. torpedo designers and the German is striking: those who designed and built the Mark-14 and -15 went on to high rank-among them, RADM Ralph Christie, Commander Submarines Southwest Pacific; and Fleet Admiral William Leahy, FDR's Chief of Staff and Chairman, JCS. In Germany, those who designed the G7a and G7e torpedoes, when confronted with their failures, were court-martialed and sent to prison.
Assume the torpedo is a dud and hits anyway. No explosion, just a small fountain of water. FDR would be commenting on the narrow escape, but would also wonder if all torpedoes are duds. He'd no doubt launch an investigation of the matter, and the complaints from all three branches of the Navy (Naval Aviation, the sub force, and destroyers) would come to the forefront. One might even see Congressional investigation-perhaps run by the committee headed by Sen. Harry S Truman (D-MO), which was ferreting waste and abuse in the war effort.