I read carefully your lecture about AI detecting "powers".Well...let me tell you something I learned so far noticing things when hunting a convoy...if you indulge me
The approach from behind the convoy won't work.Sooner or later they will come for you.If they are too many maybe you can bring down one destroyer if you are lucky and all you can get is losing time and torpedoes if you don't asses the situation correctly.But if only one ship or two are coming for you you could have one shot to bring them down , especially if they noticed you late and you had time to get out of their way.
The best way is to be in front of the convoy, to wait still and to position yourself in 90 degrees with their way.You can fire ,depends of the sub missiles ahead an backwards without them noticing you.But if you catch up with convoy from behind try to switch places and go right or left and set ypurself ahead the convoy.You just have to pay attention going behind the last destroyer in line and then lose the convoy for a while , meanwhile checking position to it from 10 to 10 minutes.That's my methods and they work 99%.