Oh, you are right, these errors do not make much sense.
They are always from black probe to red Probe. The point of the arrow is where the positive prove was.
I will try to clean up the diode later
*edit*
I was not able to uncover any markings on the diode so I eventually gave in, unsoldered it and measured it outside of the circuit.
I even put another larger diode with a visible marking next to it to make sure I do not do anything stupid with the probes.
I am now 100% sure that the diode is correct.
Oh and yes... I had it wrong before

.
But the bad news is: it makes absolutely no difference to the 5V line.
*edit2*
Tried to measure CS on IC200 (I used R228 and pin 5 of T200 so I dont short the pins).
0.001V in AC mode. I have no idea if my meter is capable of measuring AC at the frequency it needs to
*edit3*
And Im reading 0.776V on the Feedback Pin