I agree with Andres, if someone wants to have a color calibration tool in PI based on B-V or V-R color index data, then make it a separate script/tool. I hope this wonderful script can continue to be devoted to providing information, ie names, color indices, etc. Parenthetically, IMHO, the current color calibration tool in PI is terrific and for me, works great, much better or at least more consistently than when I've tried color calibration based on finding G2V stars in an image to determine the RGB ratio using ExCalibrator.
Andres, in this script I would hope you can configure it to show B-V and V-R ratios, or just B, V, and G mags, for as many stars in an image as possible. It has been my practice to use a near finished image and check the accuracy of the star color using these values. In this way, a star with a B-V index, for example, greater than 0.65 should be red and one less than 0.65 should be blue, and one with a value close to 0.65 should be white. So, if possible allow all values to be shown, ie an option to have the data unfiltered.