At least here in Argentina, after 6+2 weeks the mother gets an echography and may know if the baby is a boy or a girl. Another afer 10+2 weeks, where it's more clear. So I expect that the prediction is checked most of the times instantly.

Also, if they go to Mali again in a few years, if they by chance meet again in the airport, if it's a prediction I expect the parents to say hello and show the little boy. But in the other case I expect the parents to avoid embarrassing her with the anecdote of he failure.

She can't make a prediction if the parents don't know.

The point is not that she predicted the gender of the child. She predicts what gender the parents expect the child to be without being explicitly told.

She didn't tell me anything about the success rate. Instead she told what factors she used to make her guess. She can tell if she was right or wrong right away because the parents can say what they are expecting.