IIRC it’s designed so that similar sounding words are so far apart from each other that it’s clear that you’ve got something wrong. Meaning the w3w addresses are meant to be used with a vague idea of where you want to go.
> The overwhelming proportion of similar-sounding 3 word combinations will be so far apart that an error is obvious,
However, it continues like this:
> but there will still be cases where potentially confusable word combinations are nearby. Our Autosuggest feature actively intercepts possible errors or confusions and highlights other possibilities to the user, helping to identify what might need to be checked.
So they rely on auto-suggest and people trying all suggested alternatives.
e.g.:
https://twitter.com/matthewwilkes/status/1388772924627333121
https://twitter.com/cybergibbons/status/1387911525873197057