Wow you guys! Some serious math goin' on there . . . uhm so let me see if I understand what's being done - you're taking RGB values and calculating the correct greyscale value from them?
Does the math really matter, though? A palette is such a visual thing. Does it matter if it's mathematically sound? It has to look right to the eye. And even that is subjective. Don't get me wrong, I highly appreciate the math figures being thrown around. Greyscale conversion is the ONE thing, in my workflow, that I HAVE to use ProMotion for. Photoshop doesn't do it right. I don't know of any other software that greyscale converts a color correctly.
I was going off of this at first, to make an even ramp, which I ditched - 100 / 32 = 3.125 -OR- 255 / 32 = 7.968. 32 equal lightness steps.
I've decided to ditch lumapairs and just go with a 32 step luma ramp for the palette - here's the ramp I've worked out:

It doesn't alter the original colors much at all, while lightening up the dark end, creating a larger midtone range in the palette.
I plan to soon to fill in the missing colors. One idea I have for that is to attempt to represent each main RGB spectrum component (Red, Green & Blue) every 3-6 shades. Secondaries and even tertiaries will hopefully make a sufficient appearance. No idea yet . . . we'll see. Might get some time to work on this tonight.
If you feel like taking a crack at inputting some new colors into the future pal, by all mean go for it; would love to have another's palette attempt to bounce my own off of.