Question One: The conditional sort is based on the search:highlight, if
it is decimal, sort the putAmount and then incarnate the document.
Notice: The "Rationale" is that currency and amount must be paired. In
each search:snippet, the currency is one search:highlight while amount
another. I would imagine a pure XSLT conditional sort in below manner.

=====================================================
 B B B  <xsl:param name="sortAmount">
 B B B B B B B  <xsl:for-each select="highlight">
 B B B B B B B B B B B  <xsl:sort select="if (normalize-space() castable as
xs:decimal) then descending
 B B B B B B B B B B B B B B B  else ()"/>
 B B B B B B B  </xsl:for-each>
 B B B  </xsl:param>

What kind of value is sortAmount supposed to represent, a sequence of
sort values like the amount, a sequence of sort orders like "descending"?

 B B B  <xsl:template match="result">
 B B B B B B B  <xsl:variable name="doc" select="document(@uri)"/>
 B B B B B B B  <xsl:element name="Trade">
 B B B B B B B B B B B  <xsl:for-each-group select="." group-by="@uri">
 B B B B B B B B B B B B B B B  <xsl:call-template name="sort-render">
 B B B B B B B B B B B B B B B B B B B  <xsl:with-param name="sortAmt"

 B B B B B B B B B B B <!--B B B B B B B B  <xsl:with-param name="uri"
select="current-grouping-key()"/> -->
 B B B B B B B B B B B B B B B  </xsl:call-template>
 B B B B B B B B B B B  </xsl:for-each-group>
 B B B B B B B  </xsl:element>
 B B B  </xsl:template>

 B B B  <xsl:template name="sort-render">
 B B B B B B B  <xsl:param name="sortAmt"/>
 B <!--B B B B B B  <xsl:param name="uri"/> -->
 B B B B B B B  <Justification inDocument="{@uri}">
 B B B B B B B B B B B  <xsl:for-each select="descendant::match">
 B B B B B B B B B B B B B B B  <path><xsl:value-of select="@path"/></path>
 B B B B B B B B B B B B B B B  <highlight><xsl:value-of

 B B B B B B B B B B B  </xsl:for-each>
 B B B B B B B  </Justification>
 B B B  </xsl:template>

Can you explain where you want to sort? You create a parameter named
sortAmount and pass it on as sortAmt but I do not even see any further
sorting there that uses sortAmt.