I cobbled together a little command-line¹ program to convert LXF models to LDR. I put it in a gitlab repo here.
Contrarily to LDD’s own conversion process, it tries to convert decorations (though a lot are missing/different in LDraw) and flexible parts (though unflexed).
On the technical part: it’s source only², tested under Linux only but should compile and work on other OSes (needs Qt5 core, QuaZIP and yaml-cpp).
On the legal part: it’s GPLv3+.
Constructive comments are welcome.
¹ Yes, command-line, no GUI. Feel free to add one if you wish. A minimal GUI was added in March, 2018.
² I won’t provide binaries. Feel free to do so for your OS (pointing to the sources as per GPLv3+).