I don’t think I agree with your interpretation of the definition.

If I spell the word “pale” as “pal”, that is not an acceptable spelling for the word “pale”, even if it is coincidentally the acceptable spelling for an entirely different word.

If I asked a human editor to spellcheck the sentence: “His mouth dropped and he turned pal.”, the editor would correctly indicate I had misspelled the word.

Spellcheck hasn’t done this in the past because it can be quite difficult. But that’s a limitation of computer capability, not functionality bounded by the definition of the term “spellcheck”.