spelling and punctuation aren’t grammar pass it on
seriously, correcting someone’s misuse or lack of punctuation, or incorrect spelling, is not correcting someone’s grammar. spelling and punctuation are conventions, not part of language. grammar refers to the way information is conveyed in a language. basically, it means all those rules of a language working together when speak it. case endings, plurality, classifier words, etc.
so, spanish encodes information into a verb about when that verb happened in time, but also about who did the verb, such that you can leave off the subject of a sentence because that information is in the verb ending. english doesnt do that. well, we use -s for 3rd person singular, but that’s the only remnant of the system english used to have for that. that’s grammar. that’s the system we use to communicate information when we talk. we place prepositions before the noun, some languages place them after (thus, they are postpositions). that’s grammar.
where you put your comma and how you spell “theiyr’e”? not grammar.
written language isnt actually relevant to linguistics. how a word is spelled does not actually matter linguistically. it can help convey the idea of how a word sounds but at least for the purposes of studying a language, only spoken language (or signed language) matters.
written language is to linguistics what chemical formulas are to chemistry. chemistry will happen whether or not you write it down. language will happen whether or not you write it down.
spelling and punctuation have nothing to do with grammar