Quoting the doc you linked:
inject(true/false) If true (the default), then new phonetic tokens are added to the stream. Otherwise, tokens are replaced with the phonetic equivalent. Setting this to false will enable phonetic matching, but the exact spelling of the target word may not match.
It may explain why you get no results for exact match with this analyzer. Please consider matching your query against all analyzers for a field i.e. familyNameExact, familyNameSoundex, etc. and only adjusting the boost.
If you need further assistance please create a PR (even not working one) as it’s easier to look at the whole picture rather than snippets.