On the three ships you list:

USS Joseph Hewes AP-50 sunk off Fedhala by U-173

SS Winooski and DD 455 HAmbelton were also torpedoed by U-173 in essentially the same attack but survived .

The two merchants were two of the most exposed to such attack in the Fedhala landing transport anchorage which is why they were the ones hit.
Of the 29 Allied ships sunk during the Torch landings virtually all were by either Luftwaffe bombing attack or U-boat attack. There were three sunk by gunfire from French shore batteries that were used to make forced landings in various harbors ahead of the main landings, the Allies attempting to make a Coup de Main.