>>38299718>>38299888Kahili in the anime was suffering from a losing streak that caused her to lose confidence in herself and her own abilities as a Poke-golfer. She was trying to make herself feel better by revisiting the Pokemon School. She then ended up trying to help teach Ash and co. how to Poke-golf.
By the end of the episode, she regained her confidence in her skills and ability, and managed to win a competition. Being happy that you managed to regain your confidence AND win a tournament after beefing it so many times before is perfectly normal and understandable. Anybody would and should be happy about this.
The thing about Kahili in the games is that you barely have much in the way of interaction with her. Your biggest interaction is while challenging her to an Elite 4 match, where she she is being serious and formal.
Anime Kahili, as mentioned, was suffering from her own issues and trying to get away from things for a bit. She was basically lying to herself about her own feelings, and was just having fun helping a bunch of dumb kids learn how to play Poke-Golf. She had no real reason to keep frowning in such a situation where she could relax and enjoy her time with a bunch of kids. Not to mention she was an animated character free to show a lot more expression than her in-game model.
She ain't a robot that needs to only be frowning.
