Aligning fields based on position using XSLT

I have an XML document with records that have separate fields for subject tags in English and Spanish. Individual tags are separated by semicolons.

<collections>
  <collection name="anyCollection">
    <record>
      <field name="materia">comida; bebida; fiesta</field>
      <field name="subject">food; drink; party</field>
      <field name="recordid">abc0001</field>
    </record>
    <record>
      <field name="materia">comida; bebida; fiesta</field>
      <field name="subject">food; drink; party</field>
      <field name="recordid">abc0002</field>
    </record>
    <record>
      <field name="materia">comida; bebida; fiesta</field>
      <field name="subject">food; drink; party</field>
      <field name="recordid">abc0003</field>
    </record>
    <record>
      <field name="materia">fiesta; sombreros; música; baile; agua; cerveza; sopa</field>
      <field name="subject">party; hats; music; dance; water; beer; soup</field>
      <field name="recordid">abc0004</field>
    </record>
    <record>
      <field name="materia">comida; bebida; fiesta; sombreros; música</field>
      <field name="subject">food; drink; party; hats; music</field>
      <field name="recordid">abc0005</field>
    </record>
    <record>
      <field name="materia">comida; bebida; cerveza; agua</field>
      <field name="subject">food; drink; beer; water</field>            
      <field name="recordid">abc0006</field>
    </record>        
    <record>
      <field name="materia">fiesta; sombreros; música; baile; agua; cerveza</field>
      <field name="subject">party; hats; music; dance; water; beer</field>
      <field name="recordid">abc0007</field>
    </record>       
  </collection>
</collections>

I want to be able to output a text file with the contents of the two fields grouped and aligned by position so that I can be sure that they are mirror images of each other. Here is my current stylesheet. It produces the basic output that I want, but it does not do it dynamically. Basically, I want to be able to iterate through the contents of each field by position. I'm guessing I need some kind of recursive template or function, but I'm having trouble figuring it out.

<?xml version="1.0" encoding="UTF-8"?>
<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:variable name="field">
    <xsl:for-each  
      select="collections/collection[@name='anyCollection']/record">
      <record>
        <xsl:for-each select="field">
          <field>
            <xsl:for-each select="tokenize(.[@name='materia'],';')">
              <materia>
                <xsl:value-of select="."/>
              </materia>
            </xsl:for-each>
            <xsl:for-each select="tokenize(.[@name='subject'],';')">
              <subject>
                <xsl:value-of select="."/>
              </subject>
            </xsl:for-each>
          </field>
        </xsl:for-each>
      </record>
    </xsl:for-each>
  </xsl:variable>

  <xsl:variable name="align">        
    <xsl:for-each select="$field/record/field">           
      <languagePair1>                
        <xsl:for-each select="materia[1]">                    
          <xsl:value-of select="."/> 
          <xsl:text>_</xsl:text>    
        </xsl:for-each>
        <xsl:for-each select="subject[1]">                    
          <xsl:value-of select="."/> 
          <xsl:text>&#10;</xsl:text>    
        </xsl:for-each>
      </languagePair1>
      <languagePair2>
        <xsl:for-each select="materia[2]">                    
          <xsl:value-of select="."/> 
          <xsl:text>_</xsl:text>    
        </xsl:for-each>                                               
        <xsl:for-each select="subject[2]">                    
          <xsl:value-of select="."/> 
          <xsl:text>&#10;</xsl:text>    
        </xsl:for-each>                             
      </languagePair2>
    </xsl:for-each>
  </xsl:variable>

  <xsl:template match="/">             
    <xsl:for-each-group select="$align/languagePair1" group-by=".">           
      <xsl:value-of select="current-grouping-key()"/>           
    </xsl:for-each-group>
    <xsl:for-each-group select="$align/languagePair2" group-by=".">           
      <xsl:value-of select="current-grouping-key()"/>            
    </xsl:for-each-group>
  </xsl:template>

</xsl:stylesheet>

Here is the basic output I want:

comida_food

bebida_drink

fiesta_party

sombreros_hats

música_music

I also need to output the recordids associated with each tag, but I haven't been able to include this in the stylesheet yet.

With that information added, the desired output would look like this:

comida_food
abc0001
abc0002
abc0003
abc0005
abc0006

bebida_drink
abc0001
abc0002
abc0003
abc0005
abc0006

fiesta_party
abc0001
abc0002
abc0003
abc0004
abc0005
abc0007

sombreros_hats
abc0004
abc0005
abc0007

música_music
abc0004
abc0005
abc0007

A nice use case for fn:for-each-pair in XPath 3.0:

for-each-pair(
  tokenize($materia, '; '), 
  tokenize($subject, '; '),
  function($x, $y) { $x || '_' || $y || '
' })

Available in Saxon-PE 9.5.1.1.