I will try applying the PHC to Nykta, save it out to get the cr2 and then compare it side by side with the original. I won't have any better idea of what I'm looking at, but comparing side by side, I will spot any differences.

If nothing shows up, I'll just live with it. It could be worse: it could be a terribly complex shader that would be a nightmare to recreate every time I wanted to make some changes to it.