To conclude my story, I received a “new” pair of speakers, ie. only the speakers themselves were said to be new, the rest of the accessories in box were not replaced and that is fine. However, the speakers came in with dirt marks (clearly visible on white) and no protective film - not that it serves any purpose, just had me doubt that they are in fact new. I would expect that a premium product comes pristine from a factory to customer… The production date on the box is October 2016, same as the previous pair, but firmware was already at version 2.3.0.
The good news is that I have another 2 years of warranty starting now, no thanks to KEF, but to EU consumer law I think.
Curiously, there were a few others cases of the same issue with LS50W in the service shop…