I can only speak for France where a similar rule is in place at some uncontrolled, including non AFIS, aerodromes. The rule here is widely misunderstood by private pilots and flying clubs generally. The exemption simply allows that French is the standard at the aerodrome and not english (otherwise required by convention) so all calls should be made in French. You do not need to speak the french language but you should make all "standard" circuit calls in French.
So not too onerous other than to learn the standard position reports in french: overhead, downwind, baseleg, final, runway vacated etc.
The Chicago Convention took place on December 7th 1944. English as the recommended international language of aeronautical communications was decided much later in 1951.
Last edited by Fl1ingfrog; 7th October 2019 at 10:52.