There are many components to the AI: the sim.cfg file, sensors.cfg file, the sensors themselves and crew rating. Adjusting any will influence AI behaviour.
Building a killer AI that will detect you and kill you every time is easy, i.e. "Bungo Pete" from SH4, a IJN destroyer with an elite crew and super sensitive hydrophones. The trick is to build an AI that will act in a "realistic" manner, i.e. like a human manned escort would act at any particular time in the war.
Early war escorts have gotten an unfairly bad rep. RN fleet destroyers in the 1939 to mid-40 were actually very well trained and were staffed with pre-war professional crews. They should have a high crew rating, veteran or elite. The problem with early war escorts was their equipment, early war sonars and DCs.
The dip in crew quality occurs in mid-1940. With France out of the war, the Royal Navy was over stretched. Escort duties were taken over by smaller escorts like corvettes or sloops, many manned by poorly trained crews. The Royal Canadian Navy which provided roughly half the escorts during the "Happy Times" had very green crews.
Now back to the game, personally I would not touch the Sim.cfg file. It acts as a traffic light, "green", the AI detects you and comes gunning for you or "red", it does not detect you and goes about its merry way. It also affects all AI, air, merchant and escorts and if one detects you, the info is instantly relayed to all units in the area. TDW in IRAI had already pushed the Sim and sensors cfg files to the max IMHO, at least the ones included in TWOS.
To tweak escort behaviour, I would look more at the crew rating in the mission/campaign files and the range/sensitivity of the sensors they are equipped with.
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