http://jensteich.de/fmfaq/export/xslt-for-simple-cases/

 <!--
  xslt stylesheet importing xml data into FileMaker for easy cases
  like:
 
<root>
  <record>
    <field1>....</field1>
    <field2>....</field2>
    <field3>....</field3>
    <... any number of fields ...
  </record>
  ... any number of records
 
  'root', 'record', 'fieldx' can be any names.
 

~jens

You have way too much code - most of it will be ignored during the import.

You also have a line that shouldn't be there:

FIELD EMPTYOK="YES" MAXREPEAT="1" NAME="FeldName" TYPE="TEXT"/>

 

The entire stylesheet could be shortened to just:
 

<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="/*">
    <FMPXMLRESULT xmlns="http://www.filemaker.com/fmpxmlresult">
        <METADATA>
            <xsl:for-each select="*[1]/*">
                <FIELD name="{name()}"/>
            </xsl:for-each>
        </METADATA>
        <RESULTSET>
            <xsl:for-each select="*">
                <ROW>
                    <xsl:for-each select="*">
                        <COL><DATA><xsl:value-of select="."/></DATA></COL>
                    </xsl:for-each>
                </ROW>
            </xsl:for-each>
        </RESULTSET>
    </FMPXMLRESULT>
</xsl:template>
 
</xsl:stylesheet>

(assuming version 11 or higher).

In fact, it could be shortened even further, but that's for another occasion.