I was curious to see how oRGB worked in practice so I made some code to test this, and uploaded to a JS fiddle: https://jsfiddle.net/phv7x39q/1/

It is a very naive implementation, more work could be put in optimizing it.

Once I got around to fiddling with it I understood what the paper explained. I'm not new to colorspaces or matrix transformations but it is hard sometimes to grasp the concept from the paper.

I think you have a bug - the rotation is supposed to be in the opposite direction if the red-green value is below zero. The paper doesn't make that very clear.

Out of curiosity: when you go full throttle on red yellow, dark <-> light goes from red to orange to yellow. Is that really as it is meant to be? I'd (intuitively) expect to be able to go from orange to brown by adjusting the dark/light dimension.

This is a great paper! Thank you for sharing it. I'm not an expert by any means in color theory, but I found the paper both accessible (great diagrams!) and compelling.