Yes, it’s going to be a super fact-specific ruling in each case because what you’re trying to determine generally is what was actually agreed. (There are exceptions to this where what was written will have heavier or lighter weight.) Here though it seems like everyone at the time agreed one thing and wrote another. I’d be shocked if somehow this got the author rich even without time barring.

Completely irrelevant to this case. That's about grammar and punctuation; this is about an accounting error expressed in English.