libjingle\'s developer guide quite vaguely mentions incompatibilities between libjingle\'s implementation of Jingle and XEP-0166\'s specification. It also mentions it is inc
libjingle
exists for more than 3 years, and its protocol didn't change much. It was compatible with one of the early versions of XEP-0166... not sure now which one exactly, but I guess it was something around 0.15.
You might have better luck asking at the jdev mailing list.
All versions of this XEP are stored in a version control repository.
Anyway, many implementations use libjingle, so being compatible with libjingle might be more important for you than with XEP.