I certainly agree that there's a fine line between recording everything verbatim (not a good thing in my opinion for a whole host of reasons I won't go into here) and recording the bare minimum. There's a balance to be achieved between the two which gives context to the decision but doesn't become ammunition for those who are looking for an excuse to overturn an otherwise legitimate decision. A good experienced clerk can do this but to be fair to the inexperienced that's quite a skill. At the end of the day, a decision is a decision rightly or wrongy and one which is made by and therefore binding upon the whole.
Just to be clear, once minutes have been adopted/approved by council, they cannot be amended so to go back to the original question, yes the clerk can amend the minutes produced by the locum (and I recall doing so myself when clerk, largely to correct spellings and grammar) but once adopted, the only route is to bring the subject up at a later meeting and note any comments then.