She has no faceposing so her expression is pretty much:

Hopefully somebody will work on it. If you’ve been following me long it was the same for Midna wherein I had to keep hiding her face when doing animations but then Clatterbot fixed her right up and made her face poseable and stuff (Donan then eventually made an expandable version).

LoL’s pretty popular so I’m 100% sure someone’s gonna work on it eventually and make these models more SFM friendly. Here’s hoping Riot does a good job with Poppy’s remodel and someone imports that. Poppy best yordle.