Nintex Cloud should send out warning emails if the Google Maps API key stops working.
It would also be nice if the control's collection had an option for street, region, postal code etc. that is processed (as best as possible) from the description field of the collection when the Maps API fails to provide a verified address. If the Maps API was successfully reached, these fields would then be populated by that like how description currently works.
Thank you very much for posting your feedback on the current Google Maps control for our review. At this time, we will not be adding this request to the near-term backlog, as we are focused on other highly requested features such as Form Participant permissions, Repeating sections re-usability, etc. You may also want to consider building a custom control through the recently released Forms Plug-in feature. However, we reevaluate requests every quarter and will reach out if priorities change. Please keep the feedback coming as it is critical for our longer-term planning.