[berdario]

That's interesting, I didn't realize that IMEs would silently offer you choices in different sets/styles than the one preferred by the locale, and that OS fonts could actually hide the difference.

If you're saying that an innocent error is what happened, you'd expect to see these weird traditional-in-simplified-context characters to appear across all sections of the documents, and not clustered together in a single paragraph (since that would be evidence that a single paragraph has been written by a different author than the rest of the document)

[throwaway290]

I believe if they can make it into a document in any number of ways (copy paste, input method, etc.) and no one would be able to tell, their existence alone is not an indicator.

That different authors could have written/rewritten/edited different parts of a document at different points in time is natural, what are reasons to think otherwise?