Hi Platon,
I had neglected to look under the heading of captured & renamed - knowing the German penchant for retaining original names.
There is a contention on some quarters that Cittá di Trapani could have been torpedoed by HMS Unrivalled but I have no proof that this is a possibility.
As far the attacker of Rorqual: Italian subs had strict orders to limit their salvoes to 2 torpedoes, even on very valuable targets, due to the dearth of raw materials for their construction and high price(!). It is unlikely an Italian boat would have fired 4 at a sub, moreover, since there were no targets in the area for Axis boats, it is strange that a sub was operating there at a high risk to herself from the passing Axis convoys. Did this attack really happen? Mediterranean eels have been responsible for causing phosphorescence which was mistaken for torpedoes before, it would not surprise me if the entire episode was an allucination (in good faith of course - working on a minelaying sub requires nerves of steel).
Regards, Brian