No, if I posted the wrong link, that’s my error.
“The speech was first reported in the Savannah Republican newspaper, with this version appearing in a collection of Stephens’s papers, edited by Henry Cleveland and published in 1866.”
https://encyclopediavirginia.org/entries/cornerstone-speech-by-alexander-h-stephens-march-21-1861/
Note “a collection of Stephen’s papers.”
And the link you provided contains the quote that you say is incorrect.
Never mind reply 659.