You get a 100% torpedo solution IF you enter the 100% correct parameters (AOB, speed, distance)
For my part, i play also 100% realism (except for identifying ships - that’s my XO who does the job and open the book on the right page) and i never draw anything on map to calculate interception course or whatever...
I try to play as real capt did
I just visually estimate target course (on deck/UZO) try to adjust little by little my best trajectory, then dive at the last ultimate moment (before being spotted), and after all stopped (or at 1 or 2 knots speed) calculate with the U-Jagd chrono the target speed. If my sub is running more than 2 knots, the U-Jagd result may be wrong... so sometimes i have to full reverse my electrics to stop me!
To me it’s the most important factor to hit. The target speed.
Then i enter manually the AOB after a visual estimation. That’s the second most important factor. Usually, i can easily approach almost the 90°. But not always...
I already fired and hit with more than an 45° angle
In this case, your AOB is very important. But almost 90°, you can have little AOB error. No big deal, you’ll hit if you are within 800/1000m.
And last i enter the distance with stadimeter, but sometimes i don’t even have time... and i hit nevertheless. Distance isn’t that important, because i always try to fire very close.
In my current career, i sunk two boats at 2000m, but it was because i was absolutely sure of target speed and AOB. One was a destroyer, and was kind of very proud
To resume, playing only with visual estimations and TDC on (TDC off to enter manually the factors) is enough close to reality
(I already missed plenty of times also...)
I don’t think i would use the kind of mod your talking about.
I think it was only the Kaleun who gave the torpedo solution...and ordered to fire.