A normal local spellcheck requires you to be much closer to the word than an "enhanced" one. As an example, if I search Google for "nucrusift" ("microsoft", but typed with my right hand one space to the left, a fairly common category of typo IME), it suggests a search for "Microsoft". The built-in spellcheck in Chrome (which I'm using to type this comment) does not offer any suggestions to correct "nucrusift".
I just tried for myself, and that was the keyboard's auto-complete, not the OS's spell-check, a subtle but IMO important difference. I think it's reasonable to expect the keyboard to catch that kind of typo, given it inherently has to do that kind of fuzzy logic to determine words anyway.
When I entered that same string into iOS Safari in a text box replying to your comment, deliberately bypassing the keyboard's auto-complete, it had no suggestions.
Marking unrecognized words, suggesting spellings, and auto correct are 3 different features if you want to split hairs. The distinction is not relevant to the claim a layout aware suggestion could not be produced locally.
I didn't say it could not be produced locally. I was just providing "an actual example of what these "enhanced" spell-checkers provide over basic ones that run locally." I'm merely speaking to what is, not what could be.
