When using Waze on Android Auto (new Mazda) the buttons are selected using the touch wheel. The selection is indicated by a thicker frame around the buttons. While driving, this marking is hardly detectable. Instead a more significant colour or cycling colour pattern would help to find the selected button.

Another problem on my Mazda head unit is that it is nearly impossible to select the answer on the popup if a given event is still present or not. Using the touch wheel I'm hardly able to select yes or no, because the marking is not visible at all. This seems to be a bug.