How to convert some text in paragraph into bold xsl fo? - xslt-1.0

Question

This is how my xml looks like:
xml:
<Documents>
<Document>
<Note>
<Header>
<HeaderText> <b>Need Help?</b> Contact Our Customer Happiness Team
by phone <b>0345 00002662</b>
Mon-Fri 9am-7pm
</HeaderText>
</Header>
</Note>
</Document>
</Documents>
I want to convert some text in HeaderText in bold. E.g Need Help? Contact Our Customer Happiness Team
by phone [phone] Mon-Fri 9am-7pm
Xslt:
<fo:table-header text-align="left" border-width="0mm">
<fo:table-row margin-left="1cm" font-family="Avenir" font-size="14pt">
<fo:table-cell>
<fo:block padding-top="0cm">
<xsl:value-of select="HeaderText" />
</fo:block>
</fo:table-cell>
</fo:table-row>
</fo:table-header>

Answer 1

The <b>Need Help?</b> is just text to the XSLT processor and the XSL-FO formatter.
This is similar to XSLT - How to treat inline/escaped XML within a node as nested nodes. The advice there doesn't get beyond doing it in two passes or using XSLT 2.0 or 3.0.
If <b> is the only non-element that you need to convert into real markup, then you can do it with a recursive template:
<xsl:template match="text()[contains(., '<b>')]"
name="unescape-bold">
<xsl:param name="text" select="." />
<xsl:choose>
<xsl:when test="not(contains($text, '<b>'))">
<xsl:value-of select="$text" />
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="substring-before($text, '<b>')" />
<fo:inline font-weight="bold">
<xsl:value-of
select="substring-before(substring-after($text, '<b>'),
'</b>')" />
</fo:inline>
<xsl:call-template name="unescape-bold">
<xsl:with-param name="text"
select="substring-after($text, '</b>')" />
</xsl:call-template>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
For your sample, this gives:
<fo:inline font-weight="bold">Need Help?</fo:inline> Contact Our Customer Happiness Team
by phone <fo:inline font-weight="bold">0345 00002662</fo:inline>
Mon-Fri 9am-7pm

Answer 2

Check this Code:-
<fo:table-header text-align="left" border-width="0mm">
<fo:table-row margin-left="1cm" font-family="Avenir" font-size="14pt">
<fo:table-cell>
<fo:block padding-top="0cm">
<xsl:apply-templates/>
</fo:block>
</fo:table-cell>
</fo:table-row>
</fo:table-header>
<xsl:template match="bold">
<fo:inline font-weight="bold">
<xsl:apply-templates/>
</fo:inline>
</xsl:template>