There are two types of lion cubs in CL.
One, the rock lion cubs, exist, though rarely, up north by the dog trapper lake.
The other, savanna lion cubs (which you need for that ring quest) don't exist. I spent over 3 hours killing every savanna lion and lioness around the druid ring and the tall rocks just north of that, and not a single cub spawned. I've read on the official forums of people not finding them either. I submitted a ticket about it, but never heard anything back.
Quest reward isn't worth the effort.