Thanks for your quick response again.
Tried it, but really strange; I made the font show up in the customizer. But when selecting it shows Open Sans in the preview. Save it and look real-time, still Opens Sans. Go back to the customizer and Open Sans is selected.
Then I thought I could also do it with css. So changed H1 with the Google font family and a real different font shows up! Though in css the baloo font is set. Really weird….
So for now I keep it the old way, waiting for the client response of the site.