In the example at the start of the article, 烹, the contestant wrote "child" when the proper grapheme was "complete." That's a non-trivial error, even if it is only one stroke difference.
Even less of a difference. There's no equivalent character, so it's clearly 烹 written with an extra stroke. It's more like the difference between writing "deceive" and decieve."
I don’t think so, no. English is phonetic and so some of those spelling errors can come down to your dialect pronouncing the word differently and forgetting the official spelling. That’s now how Chinese characters work though. It tells a story, and a story with “child” instead of “complete” is a vastly different story.
Well, but as far as I can tell there is no legitimate character created by replacing complete(了) by child(子) in 烹. It does not matter what "story" it tries to tell, if someone writes "boild eggs" I'm not going to conjure up a hypothetical German etymology that might have led to "boild" that later got borrowed into English; I will understand it as a typo of "boiled".
The equivalent in English would be writing "ghyche" when trying to write the word, "fish". Yeah, that combination of characters/marks can make sounds equivalent to "f" "ih" and "sh" but it's so far off it's laughable.