Thanks Denny, I largely see your points. The distinction between convenience = webservice to redirect to canonical URL and canonical URL could perhaps be made clearer in the note. I read it as parallel URIs rather than as a redirecting service. To me the word "convenience" has a different implication, but this may be entirely my fault, I am not a native speaker either. I also agree on the choice of language prefixes, confusing as it may be, I should have know. The data plus wikidata is still confusing, but I guess you cannot avoid that one?
About the Q in front of identifiers: At the moment I see the item numbers being used in rdf:resource/about, but I understand that you may need them as element names? My understanding was that properties will be prefixed by Property: anyways.
In any event: I find the argument that a rare letter like Q is good branding not very convincing. I would suggest then a more memnonic choice, like WD2348972 or W2348972 instead. I believe the Q as prefix used in all canonical inbound links will be puzzling many people and end the explanation having to end up in the FAQ.
thanks again!
Gregor