As for iOS 11 Notifications, you can actually complete reminders from the notification. You can either force touch the notification (on an iPhone 6s or newer), or click View to see the actions for the notification. Complete is one of them, as well as “remind me in 15 minutes”.
That’s an interesting idea about filtering time alerts by location, but as of right now, iOS does not allow that granular of triggers. It’s only location or time for now, but maybe iOS 12 will be different.
I hope you continue to enjoy the app, and please let me know if you have any other suggestions!