If you want to add any custom font to the plugin. You can do this easily with the custom code below. But your custom font must be enqueued/loaded in your theme or site. Then you just need to write the font name in the function below. If you check the code you will see there is a filter hook available (eapro_field_typography_customwebfonts) in the plugin by which you can easily add custom fonts.

if( ! function_exists('eapro_field_typography_customwebfonts')) {
    function eapro_field_typography_customwebfonts_modified() {
        // your custom fonts 
        $custom_fonts = array(
            'VTF Redzone Classic',
            'SP Jupiter',
        );
        return $custom_fonts;
    }
}
add_filter( 'eapro_field_typography_customwebfonts', 'eapro_field_typography_customwebfonts_modified' );