I don't really understand what you are saying there Hadrys. Of course the TDC is useful to use, not especially difficult to understand, and perfectly accurate. Your suggestion seems only to apply at very, very short range.
I do not understand the difference in TDC solution, as shown. That must be an error somewhere, either in the game or elsewhere. Is it always like this? From the mathematics of this, the TDC should not express a difference between shooting to port and starboard. The marginal difference in the position of the bow tubes I doubt can account for this variation.
Nonetheless, it makes no difference when using smaller gyro angles.
As for how the TDC works:
The German TDC, unlike the US one, does not update range or changes in your own course. However, in some ways this disadvantage is actually an advantage, as certain aspects of the TDC will remain solved for all members of a convoy, so long as nobody's heading hasn changed.
This is the torpedo fire control problem in detail:
The TDC does the hard work of accounting for z,m and p, which is respectively the turning circle of the torpedo, the initial straight run of the torpedo before beginning the turn, and the torpedo tube parallax, the difference between the relative view from the periscope and the fact that the torpedoes exit from the front or back of the submarine.
So apart from that, you need to know the relative bearing to the target (the periscope angle), the relative course of the target (which is related to the AOB), the speed of the target and the range to the target.
Look at the AOB dial on the TDC. The "north" point of this dial represents the targets relative course. Let's imagine you are stationary lying ahead of the beam of the target, i.e. perpendicular to the target track, but before the target has reached it. You can see that in your mind, so long as neither you, nor the target change course, then as the target moves forward, the pericope angle to it will approach 000, and likewise the AOB of the target will move towards 90.
The rate of change of both is identical and this is reflected in the TDC. The AOB on the TDC once set, ie. the autoupdate light is on, the AOB will then automatically update with any change in the position of the scope.
This means that so long as neither you, nor the target chancge course, your AOB solution will be correct for every ship following the same course. A convoy, for example.
This is entirely independent of changes in range or changes in speed.
Warning! Entering AOB via the notepad on the periscope or UZO screen can be risky, and if you have time you should always update it from the TDC screen.
The reason is that the TDC AOB will update with changing periscope angle, but the notepad will not. If you enter an AOB from the notepad, that will remain on the notepad, and if you send a new range from the notepad, you may accidentally send your old, and now out of date, aob with it.