Thanks for asking.
Well, you are looking at the correct place to change fonts. Under template section, you have the option to create font templates and under typography you can change body font. In Cornerstone page builder you can select font templates and assign them to the elements to make necessary changes.
Can you please elaborate, where you are trying to change fonts? If the issue persists, can you please share login details in a secure note for us to take a closer look?