They can definitely trade knowledge of herbal remedies and folk medicine, Wen Qing always wants to learn more. (She'll pass on the cooking lessons though, leave that to someone else.)

PLEASE give her good romantic advice. They can go for a walk one day, or visit markets, or go explore some of the depths of the city, and discuss Romance. Wen Qing has never really had a female friend to discuss these matters with, so it would be great.