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I checked the ProPhoto and sRGB XYZ values, and when arranged in a matrix the rows sum to the expected D50 values. The ACES one was the only one that was abberant.

The D65 part comes in the MediaWhitePoint tag in the ICC profiles. There's no issue with that, I'm aware of that aspect of Coffin's color profiles and they have correct values in the MediaWhitePoint tag.

The XYZ values in the ICC profile which form the RGB to XYZ matrix ('forward matrix') though should sum to the connection space illuminant however, which is D50 regardless of the media white point. This is because these values take it from the connection space, which is CIE D50 2 degree observer XYZ space, to RGB, and chromatic adaptation to the media white point is done from there. See section 6.3.4.3 of https://www.color.org/specification/ICC1v43_2010-12.pdf

In any case, the sums of the XYZ values found in the ACES profile I extracted are 0.97056 1.00145 0.76492 respectively. Looks like it's almost the correct set of values, but somewhere along the way there was probably a typo. I'm not sure if this is exclusive to libraw or if this was also present in the original dcraw since I don't have the original dcraw currently.

Thanks for getting back to me!