By RTF generation, in fact, PD4ML does not embed TTF fonts to the resulting document (I am even not sure if RTF file format supports that), but writes a font family reference to let RTF viewer resolve it.

As I see in the RTF src, it refers to Win32-specific fonts, which is obviously not correct:
[language=java:288zz1ss]{f1 Arial-BoldMT;}{f2 ArialMT;}[/language:288zz1ss]

Try to disable TTF Embedding by RTF generation (exclude pd4ml.useTTF() call). Does it change anything?