"She has known how to eat well."
Translation:Elle a su comment bien manger.
the answer says: Elle n'a pas su manger bien.
doesn't that mean: she had not known how to eat well.
The French translation is clearly wrong, not only because of the switch affirmative/negative, but also because of the placement of the adverb.
I would say "elle a appris à bien manger".
elle savait comment (imparfait) = she used to know, she would know (habit/durable action in the past)