Hi @Way 
You have Apple System font on your website as well, that’s why it was applied to your widget.
However, I’ve added this code to the Custom CSS field and everything seems to be fine now:
.eapp-events-calendar-events-calendar-component{
font-family: Poppins, sans-serif;
}
Could you please check your website and let me know if it’s fine?
Also, I’ve added your idea regarding adding Poppins to the font list to our Wishlist. You can vote for this feature to keep up with all the latest updates 