GD WebFonts Toolbox Pro 2.4 is a smaller update, but the important one. It removes some outdated code (WordPress 4.0 is now required), includes support for WordPress 4.5 and support for TwentySixteen theme.
The new version now requires WordPress 4.0, and it fully supports WordPress 4.5. Also, there is a direct support for TwentySixteen theme added with previous WordPress version. List of Google fonts still has all 733 fonts, but the list is updated with latest fonts versions, variants, and styles.
If you find any errors, please report them in the support forum.