pronnouncaition -> pronunciation
inndappendent -> independent
unegspeccted -> unexpected
soggtwaee -> software
maggnificntally -> magnificently
annnesteasialgist -> anesthesiologist
That's the reason why the default maximum edit distance of SymSpell is 2.
Now, all your 6 out of 6 examples are chosen from that 1.1% margin that is not covered by edit distance 2, presenting a rather unlikely high amount of errors within a single word.
The third-party SymSpell port from Justin Willaby, which you were using for benchmarking, clearly states that you need to set both maxEditDistance and dictionaryEditDistance to a higher number if you want to correct higher edit distances. That you neither used nor mentioned. This has nothing to do with accuracy; it is a choice regarding a performance vs. maximum edit distance tradeoff one can make according to the use case at hand.
https://github.com/justinwilaby/spellchecker-wasm?tab=readme...
pronnouncaition IS within edit distance 3, according to the Damerau-Levenshtein edit distance used by SymSpell. The reason is that adjacent transpositions are counted as a single dit. https://en.wikipedia.org/wiki/Damerau%E2%80%93Levenshtein_di...