So i tried again but with just humans this time because i tried the way you described, with just slaves from the slave house. and it seems to work great. age definitely worked, this i never found a problem with. The breast size also seems work, i had a few outliers in the beginning, but then i tried increasing the weight for the breast size to test it( to a pretty high number), and i hardly found any problems then. i couldn't get Debug to work but i don't think it was needed after all.
Viewing post in Improved Random Portraits v1.0
Bothered me that it wouldn't work for a customized starting slave, so there's now a 0.6 that corrects that. Additionally I succeeded in adding a "Random Portrait" button above the normal Portrait button in the slave customization panel. Causes it to roll another portrait for the slave. Makes testing even easier as you can roll several times.