BoostedNerd

Yeah something is a bit funny with the multiple conversions going on I think.  It should only be out by a max of about +/-2°F difference, not 13.  If you temporarily set your units to metric when you initially set up the table axis it should give you something closer to expected.  
As an example, to acheive the axis values that exhibited the problem for you 160/170/190/200F, I set up the axis in °C to 71/77/88/94.
  
 
Which gives this after setting units back to US:

I did something similar to what your initial question was. I swapped out the standard style relay for a solid state mini relay and set up DC% tables that are temperature and speed . 
I had use the GP PWM calibrations. I did it for both fans that are driven by the ecu . I did it to eliminate the current shock of the fan start ups on idle. I start with 20% DC to start up fans about 3°c before the temp I want them on. I start the 2nd on 20% when first pump hits 100%DC. I also found this method controlled temperature better then just bring fans on at desired temps..