The age of cartoons is something that I never understood completely.
Given that cartoons are designed however the artist wants them to look, and then given an age somewhat arbitrarily, it's not like their appereace honestly reflects their age.
Kitty could be 12 or 21 as far as how she looks.
It's like that dilemma of the 3000 years old dragon loli vs Jotaro. The first one is technically legal because she's older than fucking Methuselah even though she looks like she still attends kindergarten, while the second one is not legal because, even though he looks like a fusion between Schwartzenegger and Clint Eastwood, he's 17.
To me, the age of fantasy characters is an absurd concept, but if the law says you can't have erotic imagery of supposedly minor characters, what stops you from saying "this fantasy minor is aged up in my smut to the required legal age"?