I don't think there is a separate font cache for Office 2016. You could trying clearing all font cache data from the drive.
Close all running applications. From an administrator account, open the Terminal app and enter the following command. You can also copy/paste it from here into the Terminal window:
sudo atsutil databases -remove
Terminal will then ask for your admin password. As you type, it will not show anything, so be sure to enter it correctly.
This command removes all font cache files. Both for the system and the current logged in user account. After running the command, close Terminal and immediately restart your Mac.