I went back in and modified the XSLT that was processing the given names to now read:

<xsl:variable name="ref_id">
    <xsl:value-of select="@ID" />
</xsl:variable>
...
<xsl:for-each select="name">
INSERT INTO authors (id, ref_id, given, family, role)
VALUES(
    UUID(),
    <!--(SELECT id FROM citations ORDER BY added desc limit 1),-->
    '<xsl:value-of select="$ref_id"/>',
    <xsl:for-each select=".">
        '<xsl:for-each select="namePart[@type='given']">
            <xsl:value-of select="."/>
            <xsl:text> </xsl:text>
        </xsl:for-each>',
        '<xsl:value-of select="namePart[@type='family']"/>',
        '<xsl:value-of select="role/roleTerm"/>'
    </xsl:for-each>
    );
</xsl:for-each>

It looked like the SQL to grab the last item didn’t always return a record for whatever reason (a locking issue?). Since there was already a key in the field, I just switched over to use that in the inserts. Still need to go through and regularize the fields so MySQL isn’t attempting to pull a foreign key index on a variable width field, but this is an update to yesterday’s code.