I have spent hours on research now, but i can not find a way to see cyrillic characters in a generated pdf.
From docx there was a xslfo generetated. If i open that, the cyrillic characters are all ok. By converting the xslfo to pdf i get the "###" for missing characters in the pdf (of course, because the standard fonts do not have them).
So i tried to embedd the fonts in the docx ...