I have gone now through several dozens of created lucky mobs and I started to notice a trend.
I always assumed that a lucky mob would simply be something like you actually roll for e.g. 100 kills. However what I experienced was something different.
When I hunt for geppettos I would always get exactly one Geppetto leave if I managed to create a lucky one. Not 0 not 2, but exactly one. One would expect to be divergence if it was indeed rolling, but it seemed pretty fixed to me.
Going for gigantic shinbone I also have to say that all my shinbones are not from lucky ones. I got plenty of lucky hogma warriors but not one dropped a gigantic shinbone. It is always 1x husk, 1x kris recipe and 1x shieldbreaker recipe. Again one would expect divergence. Maybe 2x Kris, 3x kris recipe.
So for know my conclusion is that a lucky mob means nothing different that it drops everything that has a dropchance of 1% or higher guaranteed + whatever the base loot of the mob was.
So I ask of you that if you grind via change to check the base drop of the lucky mob before killing it and tell me if this preliminary assumption is off.