"Child-like facial features" is not an objective characteristic UNLESS you apply technical rigor to the anatomical structure. In this case there are differences between a child and an adult.
There are a lot of people that claim their avatar is 18, which is a legal adult in most countries. How are you going to 'objectively' determine if the facial features of an 18-year-old vs. a 17-year-old?
Same goes for clothing. I have, in my inventory, a sweatshirt with a teddy bear on the front. Is that childish clothing?
None of these things alone are objective when it comes to determining a violation of a rule. When you start combining traits, however, then you start to get a little closer.
Is the avatar child-sized, has child-like proportions, is roleplaying as a child, is using child-like speech, is dressed like a child (still not sure about this one), AND engaging in something they shouldn't be? If all the evidence lines up properly, then sure, I can see how that would be a violation.
Simply being short, having a youthful face, and wearing a teddy-bear themed shirt is, I would argue, NOT enough to make a judgement.