This is awesome! I find Fantastical's presentation to be very poor (though love their input), Sunrise is now on the way out... The UX you came up with is amazing!

I'd pay as much as I paid for Fantastical for your native iOS app with CalDAV support, right now. Even more, to make sure you keep developing it.

If you're certain it has to stay free, please consider open sourcing it. Shopping for critical Apps every three years 'cause authors got bored of it is painful.