Hello,
Right now we can offecr to use the custom fonts feature in our XStore Control Panel -> Custom fonts, only. After you upload the font you may select it in the list of Typography fonts (Theme Options -> Typography) -> http://prntscr.com/vobjsf . So that uploaded font will be loaded locally and as we understood you right it is the main question you asked us for.
About google font “problem” we will take a look closer and try to find the solution if it won’t break anything. Thanks for sharing the details.
We are ready to give you a refund if you are not satisfied with using our theme. Refund request can be submitted here – https://themeforest.net/refund_requests/new
Regards