What I had in mind was: If the magenta offset is a constant for any particular camera, rather than something that changes during the day - will it not automatically be corrected if one makes a custom profile for that camera?
When running the Chart Wizard of the DNG Profile Editor, the ColorChecker chart as shot gets automatically white-balanced (based on the second brightest neutral patch i.e. light gray), before the Hue/Sat.-corrections are built per color patch. However, the Temp/Tint adjusts from this preceding white balance do not
flow directly into the profile e.g. by ruling white balance calibration in the Color Matrices pane.
It would not necessarily be wise to have this auto-included at this stage, while the software cannot differentiate between the two effects:
a.) the variance of natural occurring daylight perpendicular to the Daylight curve or Plackian locus (as shot).
b.) a systematic offset with Tint introduced by the camera/sensor.
Anyway I was referring to DNG profiles and the DNG Profile Editor.
ACR does not take ICC/DCP profiles. No idea what related profiling software does in this respect.
The manual of Raw Therapee (version 4.0.9, page 31) has a table for temp and tint values for neutral rendering for a number of cameras. The tint values range between about 0.9 to 1.1. I wonder how this relates to your figure of plus-minus 10.
Interesting though !
Best regards, Peter