The "fix" fixes the historical performance of the torpedo, but from a player's perspective, it breaks them... lol - The U-Boats were "Wolves Without Teeth" for a time, while the BdU tried to determine why their torpedoes were running deep and / or not detonating. Very similar to the US issue with their Mark 14 torpedoes...
https://digitalcommons.georgiasouthern.edu/etd/599/
Click on the title link on that page, and it will open a pdf the fellow wrote.