Typo-swatting

[Kilroy]

I have for the last little while been making typographical corrections to a story I downloaded from a site for my own use. The original had many, many such errors since the author used a phone's keyboard to do their text entry. 
I have no plans to repost the corections, but I do have a question I would like people's opinions on: when does such correction becomes actual copyediting? 
Along with mispellings I have been changing word forms when I thought the writer used the wrong form (using a verb as a noun or adjective as adverb, for example.) I am not any sort of expert in grammar and usage, just a reader. 
Also, does anyone have ideas as to how much editing should be done in dialogue specifically? My thought has been that characters should be allowed to make usage errors if it is part of their personality.


Kilroy

[Bob Schroeck]

You're doing copyediting, period. If you're addressing massive systemic problems in the work you are copyediting it.

(To be honest, if you're only having to fix the occasional thing here and there, you're still copyediting, just not hugely so.)

On the subject of dialogue, you need to make the distinction between errors on the part of the author and eye dialect -- the latter is the deliberate use of misspellings to establish a character with poor education, a strong accent, and so on. Eye dialect is a common tool of writers and is perfectly fine. I've used it in Drunkard's Walk -- Doug, for all that he's an Ivy League-educated genius, dips into eye dialect when he's being especially informal -- and in things I've written for My Apartment Manager Is Not an Isekai Character like Ranma Saotome's voice. If the author, however, is prone to systemic errors in grammar and usage, you'll need to figure out whether or not the character is supposed to talk that way, or if the writer's errors are changing how he should be perceived.