You are correct that this isn't "new" since this census has been published for years, but it has not been mentioned here on this forum. And it is new to me (before now I'd only seen postings about it, not the actual census). That's what I meant.
And you are also correct in saying that we don't know where Mary, Sarah and Phillip were born. All we really know (unless someone out there has more info) is that he registered his family of six in the Granville Township Book in 1765.
However, there was no column for Canadian in the 1770 census, so he couldn't indicate were Timothy and Susanna were born. His wife *was* born in MA, we know that from the Sudbury vital records. I believe that is why Andrew listed all his children and his wife as American.
So, I believe this shows that Andrew was the Irish person and is a much simpler explanation than saying Sarah considered herself Irish. I believe it might also explain why we haven't been able to find Andrew's birth record or determine which of the many Andrew Whites in MA was him.