Hi there!
The $(twitch ..) variable retrieves a whole host of useful information about a stream, but cannot retrieve whether a currently live stream is flagged as mature or not. I want to use this in a couple commands, and haven't found any other custom APIs that can get this information either–unless I were to make my own and query Twitch directly.
Since this information is available in the Twitch API (endpoint /streams, in 'is_mature'), I can't imagine this would be a difficult feature to add.
Thanks!
Mmarss