Output prefix [Language: en] in format-date() still not solved in saxon.
I've used latest saxon release - downloaded yesterday from sourceforge

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns:xs="http://www.w3.org/2001/XMLSchema"
  exclude-result-prefixes="xs" version="2.0">
  <xsl:output method="text"/>
   <xsl:template match="/">
       <xsl:value-of select="format-date(current-date(), '[D]-[M]-[Y]')"/>
   </xsl:template>
</xsl:stylesheet>