Something not mentioned before (I think) is that the w3w algorithm must – to some extent at least – vary between languages – e.g. bahn.bahn.bahn (not to be confused with barn.barn.barn) is the same as, using English, repack.twisting.frosty – i.e. what the german version gives as the same word thrice, the english version gives as three different words.
And another issue – while w3w may be multilingual – in many places it can only handle two alternatives: how does someone using, e.g., English and Zulu share location with someone using, e.g., Afrikaans and Xhosa? (To name just four of South Africa’s many languages)