are you specifying in your application, in the about section or 'third party licenses" that some of the content is the property of TwitchTV ? You have to specify it so user aren’t thinking you are part of Twitch staff or that it’s an official Twitch Application.
Also, add to the API some legal documents from Twitch like usage license of the API (? not sure it exists, it’s an example).
I hope this helped,
Have a great day!