Hi MattG, I have taken a look in your thread. You basically get the same results as I did. I have compared the values of m^0.2 and log2(3)^log10(m) for x element of [0.0001,1000] and the difference is <0.0006. But I never looked into the relation between my coefficient and bias. I got roughly the same factor as you did for all the planet-types.
It was more the terraformable bonus section I thought might help you. It's certainly a factor of the pre-terraformable bonus (and therefore mass), but the key part being it seems to be split into 34 "chunks" (z in my formula). Once you account for this it should make deciphering the bonus a bit easier. ~80-90% of the HMCs I investigated had z as 34 as did all but 1 earth-like, but there was quite a variance in water worlds. Once you can work out the value of z for each world, it might help determine what z is actually being determined by - assuming this is something we have access to in the system information. It also helped confirm that the formula for water worlds and earth-like worlds is the same, but that ELWs have z as 33 or 34.