La librairie Javascript Highcharts utilise la librairie Java Batik (libbatik-java sous Ubuntu et Debian) pour convertir le SVG vers une image PNG, JPEG ou encore en PDF.
L'erreur "Error while setting up fonts" :

Converting e187bbbb4d20a234baaba37e93601901.svg to /tmp/e187bbbb4d20a234baaba37e93601901.pdf ... org.apache.batik.transcoder.TranscoderException: Error while setting up PDFDocumentGraphics2D
Enclosed Exception:
Error while setting up fonts
at org.apache.fop.svg.PDFTranscoder.transcode(PDFTranscoder.java:189)
at org.apache.batik.transcoder.XMLAbstractTranscoder.transcode(Unknown Source)
at org.apache.batik.transcoder.SVGAbstractTranscoder.transcode(Unknown Source)
at org.apache.batik.apps.rasterizer.SVGConverter.transcode(Unknown Source)
at org.apache.batik.apps.rasterizer.SVGConverter.execute(Unknown Source)
at org.apache.batik.apps.rasterizer.Main.execute(Unknown Source)
at org.apache.batik.apps.rasterizer.Main.main(Unknown Source)
... error (SVGConverter.error.while.rasterizing.file)

La solution (pour un document root apache2 sur /var/www) :
mkdir -p -m 0777 /var/www/.fop

Source :
http://stackoverflow.com/questions/8505581/svg-generation-with-fop-doesnt-work