A few picky technical things -
The KDB hydrophone rotates on its side through the forward torpedo hatch
That's not how it should be!
The IXD2 shouldn't have one screw inactive when recharging. Unlike all other U-boats, it had a 2nd set of diesels which it could use to recharge batteries independent of propulsion.
The IXD2 seems seriously out of trim when underwater. The bow planes are always down and the stern planes are up (meaning it's bow-light), and the boat bobs up and down while traveling at depth. It should probably be trimmed a bit more neutrally.