My english vocabulary is too poor to explain it accurately but you need to understand that CRI is only an idea of how rich a spectrum is for some sample colors. CRI rating is made by measuring spectrum of reflectance (of a few sample colors).
A higher CRI means a richer spectrum. It doesn’t meant that all CRI 90 spectrums are equal and will show differences in colors the same.
Without considering your cones in your eyes, you see colors because object are reflecting a part of a spectrum. If there is low red shades in your LED’s spectrum, red, brown objects and all objects with few or rich red shades won’t reflect those red shades that are not in this particular LED’s spectrum.
The higher the CRI the richer the shades. A nichia CRI=90 with R9=50 has (or will show) less shades of red colors than a CRI=90 with R9=80.
White wall hunting even with different whites is really not a good way to judge CRI.
I remember this CPF’s thread which convinced me to “invest” in an HDS flashlight that was one of the rare HI-CRI flashlights several years ago.
HI-CRI vs LOW-CRI
Temp, tint and CRI, each one has a real and different influence on how colors are reflected and perceived.
Temp is obvious and can be judged with any color because it is just a white balance.
Tint is rather obvious too.
CRI is more subtile and need a wide range of natural colors and artificial colors to measure its benefits.