xPath oddity where predicates are somehow necessary - xslt

Question

This may seem like an odd question as I did find a working solution, but can anyone tell me why my first xPath below works and the second one does not? I did include the enes namespace in my XSLT.
Solution A works:
<xsl:copy-of select="document('my_document_of_citations.xml')//node()[namespace-uri()='enes' and local-name()='section' and position() = $section-pos]/node()[namespace-uri()='enes' and local-name()='litref']" />
Solution B does not work:
<xsl:copy-of select="document('my_document_of_citations.xml')//enes:section[position() = $section-pos]/enes:litref" />
Here is the stylesheet, with only the code in a non-germain template and function omitted:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet exclude-result-prefixes="enes thieme xhtml xlink xs" version="2.0" xmlns:enes="http://www.thieme.de/enes" xmlns:thieme="http://www.thieme.de/enes" xmlns="http://www.w3.org/1999/xhtml" xmlns:xhtml="http://www.w3.org/1999/xhtml" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:func="enesfunc">
<xsl:output method="xml" indent="yes" version="1.1" omit-xml-declaration="no" encoding="UTF-8" />
<xsl:strip-space elements="*"/>
<xsl:template match="/">
<xsl:apply-templates />
</xsl:template>
<!-- Identity Transform -->
<xsl:template match="#* | node()">
<xsl:copy>
<xsl:apply-templates select="#* | node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="part[#type eq 'content']/section[#level eq '1']">
<xsl:element name="section" xmlns="enes">
<xsl:attribute name="level" select="1" />
<xsl:attribute name="id"><xsl:value-of select="./#id"/></xsl:attribute>
<xsl:attribute name="counter"><xsl:value-of select="./#counter"/></xsl:attribute>
<xsl:apply-templates />
<!-- Insert a level 2 section with the references for this level 1 section from references_by_chapter.xml here. -->
<xsl:element name="section" xmlns="enes">
<xsl:attribute name="level" select="2" />
<xsl:attribute name="type">
<xsl:text>literature</xsl:text>
</xsl:attribute>
<!-- Get the absolute position of this section within the document. -->
<xsl:variable name="section-pos" select="count(./preceding-sibling::section) + count(ancestor::node()/preceding-sibling::node()[local-name() eq 'part']/node()[local-name() eq 'section']) + 1" />
<!-- Copy extracted references from xml here -->
<xsl:copy-of select="document('references_by_chapter.xml')//node()[namespace-uri()='enes' and local-name()='section' and position() = $section-pos]/node()[namespace-uri()='enes' and local-name()='litref']" />
<!-- <xsl:copy-of select="document('references_by_chapter.xml')//enes:section[position() = $section-pos]/enes:litref" /> -->
</xsl:element>
</xsl:element>
</xsl:template>
<xsl:template match="section[#level eq '2']//text()">
<!-- code to transform level 2 sections here. -->
</xsl:template>
<xsl:function name="func:myStrFunc">
<!-- more code here. -->
</xsl:function>

Answer 1

Simplifying the code to remove irrelevant detail, consider
child::x[position()=2]
versus
child::*[name()='x' and position()=2]
The meaning of these two constructs is quite different. The first expression considers all the child elements whose name is 'x', and then returns the second of these. The second construct considers all the child elements, and then selects the second child provided that its name is 'x'.
Which of these "works" depends of course on what your requirements are. Both of them are correct, they just do different things.