Hello @salesgenomics,
Great question!
Although custom fonts such as Google, Adobe, or self-hosted fonts are supported within Klaviyo, their support does not extend to all blocks within Klaviyo. As highlighted in the How to Add Custom Fonts in Email Templates article:
In order to use custom fonts, the code must be manually added to each message you send. The font will not be available in the dropdown menu within the template editor, and custom fonts are not supported in product, button, or header/link blocks.
At this time, custom fonts can only apply to Text Blocks, Table Blocks, and Split Blocks utilizing the Text Block function. I would be more than happy to share this feedback with our Product Team.
Thanks for being a member of the Klaviyo Community!
David