I think
you should say transform than translate.
Since XFDL is XML, the easiest way would be to do a XSLT (XSL Transformations)
Current w3c XSLT recommnedation is XSLT 2.0 and as far as I know only the Saxon 8 processor supports XSLT 2.0 (with XPATH 2.0) (The Schema aware version of Saxon is not free however). However there should be a number of XSLT processors supporting ver 1.0.
Do a bit of googling and there should be plenty of resources for ver 1.0 and perhaps 2.0 as well.