The problem is not related to observer variation nor sensor quality - it's a problem with CIE 1931 CMF.
It is also related to observer variation as there variations in response to spectral spikes and ratios of various cell types that can skew how primaries with different spikes when used in a simple tri-stim color-management system look relative to one another.
NEC PAxx2 series are calibrated with narrow band Konica-Minolta CS-2000 spectroradiometer, and all users are reporting agreeably they're observing a green cast, and after they enable metameric correction the display gets perceptually more neutral.
I'm not sure it is more perceptually neutral, is it really or is it simply closer to the typical look of a standard gamut LCD display?
As I said, if anything the real life color check chart whites looked a bit more like they did on non-metameric toggled wide gamut monitor to me, although in all three cases they looked different.
Maybe standard gamut LCD are closer, but I have some doubts.
Anyway the metamerism toggle maybe made the grayscales look a bit more similar but other tones became even more different so I didn't find the toggle really worked out so well. I'm pretty sure NEC ships the screens with metamerism toggle OFF by default.
D65 is hypothetic illuminant, so may I ask how did you illuminate the CC using non existing light source?
Just got as close as I could using indirect sunlight of the proper atmospheric conditions and at the right time of day to get reasonably close.
Anyway, it's not about monitor to print match, it's rather about monitor to monitor match.
It depends what it is about. And soon enough standard gamut LCD tech will go the way of the Dodo. I don't know how LCD's of standard gamut have become THE thing to match now and forever.