I checked and I can say that the current version doesn't create the fo_usable_fonts table for all of the sites on a multisite WordPress setup. It just creates one table rather than having a table per site on the network. Also, this means any site other than the main one on a WordPress Network will be unable to define fonts using this plugin at this time.
Ideally, each site should get its own table for the font settings. Otherwise, the settings page should be shown in the Network Admin settings if it's universal for the entire network of sites.
I have also posted this on the plugin's WordPress.org support forum at: https://wordpress.org/support/topic/doesnt-save-fonts-when-adding-with-a-wordpress-network-multi-site-setup/
I checked and I can say that the current version doesn't create the fo_usable_fonts table for all of the sites on a multisite WordPress setup. It just creates one table rather than having a table per site on the network. Also, this means any site other than the main one on a WordPress Network will be unable to define fonts using this plugin at this time.
Ideally, each site should get its own table for the font settings. Otherwise, the settings page should be shown in the Network Admin settings if it's universal for the entire network of sites.
I have also posted this on the plugin's WordPress.org support forum at: https://wordpress.org/support/topic/doesnt-save-fonts-when-adding-with-a-wordpress-network-multi-site-setup/