you have used xsl:copy which copies an element (along with its namespace
context) from the source rather than use a literal result element, or
xsl:element which generates an element node using the namespace context
in the stylesheet.

You mean something like this

<xsl:template match="chapter">
<xsl:element name="chapter">

<xsl:template match="chapter">
<chapter>
...

<xsl:attribute name="aid:pstyle"/>
<xsl:attribute name="aid:cstyle"/>
<xsl:copy-of select="@*"/>
<xsl:apply-templates/>
</xsl:element>
</xsl:template>

I did tried this but do not know what could be the reason for not
outputting.

<xsl:template match="/x:book">
<book>
Could you be please more clear about this??

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