The JSON-LD presented here has been generated by converting the RDF/XML source using the very helpful RDF conversion service provided by the E-Business and Web Science Research Group at Universität der Bundeswehr München.
We're not very happy with it, not because of the conversion itself (which appears to be excellent), but rather because we think JSON-LD greatly benefits from being generated directly rather than converted from RDF/XML.
We've put generating JSON-LD directly from the original source data, finely tuned, near the top of our todo list. So, expect what's here to change somewhat. Suggestions as to the best way to go about this would be very welcome.