I'm not sure how this keyboard could work any other way - the whole value prop is that you can search from the keyboard, and it would be pretty hard to send your search queries to google if it couldn't send the things you type to google.

the app store description is pretty clear on what it actually sends to google, and it's actually less than what most keyboards send - swype, the standard google keyboard on android, and i think most others send everything up to their respective servers so they can sync personalized predictions across devices, this keyboard only sends the queries that you explicitly ask google to search for.