If you're trying out the customisation of PDFs by modifying the XSLT, you might want to try changing the font that is used.  There are four available:

• Helvetica (which is the default)
• Times New Roman
• Courier

Here's an example of how you can specify the font

<fo:flow flow-name="xsl-region-body" font-family="Arial" color="rgb(0,0,0)">