Back to Search-quality baseline: acronym / synonym recall (Phase 1.4, v1.2.0 candidate)
Search-quality baseline: acronym / synonym recall (Phase 1.4, v1.2.0 candidate)

The 4 Wins

QueryTop-1Why this works
wlanapple-docs://corewlan (rank 1)wlan appears in CoreWLAN's framework identifier directly; FTS5 finds it without needing the synonyms table
mpsgraphapple-docs://metalperformanceshadersgraph (rank 1)The synonym mpsgraph is a partial-token-match of the framework's identifier; the long compound name's BM25F favours the exact-prefix match
spriteapple-docs://spritekit (rank 1)sprite is part of spritekit; literal substring match
locationapple-docs://corelocation (rank 1)location is part of corelocation; literal substring match

All four wins are explainable by literal-substring or prefix-token matching, not by synonym lookup. The synonyms table may not be contributing to these results at all.