The Hedgehog showed up in 1942, but similarly it didn't score a kill until Nov 1942 and didn't really become a problem for the U-boats until sometime in 1943.
The RN experienced a number of problems introducing Hedgehog to the escort fleet which lasted into 1944 and meant it wasn't a very popular weapon until then.
To quote the Admiralty April 1942 Monthly Anti-submarine Report, Hedgehog was
"a weapon of precision which requires for success a skill that can only be obtained with adequate training and practice." Unfortunately it was rushed into service without provision for training anyone other than the anti-submarine officer on each ship. His job in training the Hedgehog crew (who in the early days in the River class frigates at least were also responsible for manning the forward gun) was made more difficult by a lack of adequate manuals and standardised procedures.
Some of the early ships fitted, went without proper fire control.
Actual operation of Hedgehog was complicated. There were safety switches, as well as safety pins and fuse caps on each of the 24 bombs to be dealt with before the weapon was ready to fire. And it had a lot of electrical connections that did not like getting wet.
Ammunition was initially unreliable. In one incident in March 1942 on the destroyer Keppel, 5 bombs misfired (one landing on the forecastle) while the others entered the water irregularly and no explosions were heard. This was put down to damp having penetrated the firing circuits.
The bombs each weighed 63lb and proved difficult to handle and load accurately onto the spigots in the bad North Atlantic weather, with the crew exposed on a forecastle that was often pitching and rolling heavily with heavy spray being thrown over them. The USN tended to operate in the generally calmer waters of the Central Atlantic and Pacific so would have less of a problem in this regard. To give that some context a shell for an RN destroyer weighed about 50-62lb depending on calibre, and was being placed into a loading tray along with its separate charge before being rammed home.
There were weather limitations affecting its use.
Because the Hedgehog bombs only exploded if they hit something, there was no positive morale effect of big underwater explosions on the crews of escorts and merchantmen and no negative morale effect on the crew of the U-boat being attacked.
While you noted its first success in Nov 1942, it is worthy of note that only 16 Hedgehog salvoes had been fired against confirmed U-boat targets up to that point. Wiki says 100 ships had been equipped by the end of 1942. That would have included 12 River class frigates, which was the first class designed for it (although it was a late addition during the design process).
As the war went on improved ASDIC sets were fitted which made the use of Hedgehog easier. For example the Q fittings on Type 144 and the later Type 147 that was retrofitted to some escort vessels.
It was early 1944 before a detailed study of Hedgehog performance was undertaken at Londonderry in Northern Ireland, one of the big escort bases in the U.K. From that came better training, maintenance and procedures. The Admiralty Monthly Anti-submarine report for April 1944 noted
"The results were remarkable. Within a very short time, the percentage of hits obtained at sea during exercises rose from ten per cent to fifty per cent." And that improvement flowed through into operational success. By the second half of 1944 a success rate in the RN was up to 37%, making it almost as successful as the double Squid on the Loch class frigates.