Which is weird is that some problematic mergefields are wrapped in XML.
E.g. the displayed field name (in Word) is "ih16_nummerierung_stromkreis:aufgabe_dringlichkeit" where the xml content displays
<w:r>
<w:instrText xml:space="preserve"> MERGEFIELD ih1</w:instrText>
</w:r>
<w:r>
<w:instrText xml:space="preserve">6_nummerierung_stromkreis:aufgabe_dringlichkeit \* MERGEFORMAT </w:instrText>
</w:r>
This seems to puzzle docx4j

Are there any switches in Word or docx4j which will change the default behavior?