Hello Oliver
Richtextitem are littlebit a difficulte Story. When you use a new "XPage - only" Application with databinding to richtext elements, this elements where saved as MIME elements. And this elements can easily converted in HTML. There are some helper classes in the XPage Framework, but transforming "old" rt elements is much heavier.
But this is only one side of the medal. On the other hand, we must find a way how POI can handle HTML to the word document. I didn't check this. If you know how to do this, please let me know.
And if you find a way to bring HTML Code correctly in the word document, then you can use the postGeneration Method to apply this to the document (until we have decide to support this feature request).
Best regards
Christian