Is it Mori or Nakamura? It's a Mill/Turn right!
9311 is a measurement in the X direction (not normal to the angle you are measuring).
I'll run through the maths when I get chance - #805 is the calculated taper angle (nominally 18.104), what are you planning to do with the result of #806 (why are you multiplying the deviation by .005 or .006 depending on output)? I assume this gets fed back into the tool path some how?
I can see you are adjusting the tool offset (I think - not exactly sure what #15011 is) by the measured size error of the gauge point. How do you know what is X & what is Z deviation - does it matter?
On Mill/Turns you need to be sure the 2 points you probe are aligned in the Y axis or your angle will seem wrong.