As far as I'm aware countries fall broadly into two camps. Camp 1, USA for example, is concerned purely with the abuse of children, i.e., anything that depicts or is constructed of pieces of real children is illegal but other things such as drawings, stories, adults role playing, etc is not. Camp 2 outlaws any representation of it whether or not a child was involved.
Nowhere will a training set featuring pictures of naked children be legal.
Nowhere will a training set featuring pictures of naked children be legal.