This has been fixed in ClarisWorks 2.1v3 and above.
Claris has confirmed that some customers may see the following alert, "This document uses fonts not installed in your system." This alert may occur upon opening documents created with ClarisWorks 2.0 with their updated ClarisWorks 2.1v2.
The alert lists the "missing" fonts by number. Clicking OK opens the document and shows the fonts that were reported missing. This has happened on systems where no fonts have been installed or deleted. Therefore it seems that the alert is erroneous.
Claris Engineering is aware of the issue.