Where
Settings → Advanced → Fuzzy Pinyin lets you tick the pairs you need.
Recommended pairs
- zh/z, ch/c, sh/s (retroflex versus flat);
- n/l, r/l (common in some dialect areas);
- an/ang, en/eng, in/ing (nasal endings).
Trade-off
Fuzzy pinyin cuts errors but increases candidates and lowers first-choice accuracy slightly. Only enable the pairs you genuinely confuse.