Not perceptually uniform?

Instead of JCh, it looks like this should be constructed in CAM02-UCS space (expressed in cylindrical coordinates) which has a different lightness curve and chroma(/colorfulness?) curve.

https://github.com/matplotlib/matplotlib/issues/6033#issuecomment-412318447 and https://github.com/matplotlib/matplotlib/issues/6033#issuecomment-412367529

("the new uniform colour spaces based on CIECAM02 by Luo et al. (CAM02-UCS, CAM02-SCD and CAM02-LCD)", so CIECAM02 itself is not a uniform color space)

and even after fixing that, it might still not be technically correct to call it "perceptually uniform", but I think "perceptually uniform in lightness and hue" would be correct.