Using two different fonts on a mobile application

In my mobile app, I use two fonts; MaaxRounded for h1-h6 and Roboto for paragraph and description text.

My co-worker asked why I was using two fonts, and I at first didn't have an answer. After thinking it through, I answered that it's good for contrast and better hierarchy. My co-worker, however, insisted that I should use just one font.

What do you think of having two fonts on a mobile app? Is it better than one or not?

Here are some example pages that I made: