The way I heard it, a spokesman for the Mueller investigation stated simply that the report was not accurate. Simply that.
Not that it was partially accurate, not that they got it a little bit mixed up, not that it as anything but wrong.
Buzzfeed can stand behind it all they want, that doesn't make it any more or less accurate. Just that they printed what was reported to them in good faith.
Good coffee, good weed, and time on my hands...