It might be a good idea to remember that, when quoting anything from an ICAO Annex, it is not law. Contracting States make it into law through their own legal processes and should notify any differences in their AIP. This might be a good place to start your research ac500u.
If there's no reference to "displaced thresholds" you might be able to infer that the national aviation laws in the particular country fully reflect the Annex 14 specifications. If so, you probably need to see what clarifying information is provided in the AIP. After checking all of that, you'll probably need to consult a lawyer who is conversant with the laws of that country.