Thank you, Solidagold and angst! ^^
Exciting news! I have (slowly) started updating this guide again. Upon getting to the November 2015 PPS cat owl litter, I reached a bit of a road block. The last outcome in this litter was never confirmed on the original discussion thread, and there was no real consensus about what this cat was.

The theories I saw were barred owl and spotted owl, but I did not quite agree with those. The outcome is too dark and solid-colored. My personal theory was that it was a darker species of owl in the
Tyto genus, as the facial pattern matched that classic barn owl look. (I'm also personally a fan of those lesser known owls, so I was biased!) I thought it could have been a
sooty owl, but this wasn't quite right either. There aren't enough spots on the outcome. The
Australian masked-owl and the
ashy-faced owl are other beautiful darker owls that could have fit.
But there was no way for me to confirm these theories without reaching out to Saikiyo, so I did! And the answer was simpler than I was making it out to be (and right in front of my face) - melanistic barn owl! Obvious in retrospect, and maybe that had been stated before on the forums, but I wasn't able to find it. Thank you so much to Saikiyo for solving that mystery!