Just checking if we do understand this right...
JasperReports is able to use all fonts available on the system and print them to a physical printer (or preview the report)
If the report has to be printed to a pdf, the usage of fonts is limited to only the fonts which are provided as a jasperreport font extension.
(This sounds weird to us as the developer now has to provide fonts in the jar which are already available on the system, also the legal aspect is a problem)
Yes, your understanding is correct.
Working with font extensions is the recommended way to ensure that fonts will be available for generated documents (not only PDF) on any machine in any environment.
Anyway, in particular situations like this one, you still could make use of style attributes such as pdfFontName, pdfEncoding and pdfEmbedded.
I hope this helps,