Using two different fonts on a mobile application

I have an issue of using fonts in a mobile app. At first, I used two fonts for a mobile app; MaaxRounded for H1-H6 and Roboto for Paragraph and description text.

But my co-worker asked me why are you using two fonts? I didn't have an answer at that time but then I thought it's good for contrast and better hierarchy. But he insisted to use just one font.

My question is, 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:

Thank you very much.