Who are those “some” that think Chazal messed up the years? Talmidei Chachomim or secular historians?
Notice how you changed my connotation from being on purpose to being an error. Why did you do that?
Where is this famous question discussed in Rabbinic literature?
I don’t know.
Why not assume the error on the part of the secular historians? Why assume the error to Chazal?
Who said anything about an error?
And what is the relevancy of the year 6000?
Someone else will explain this to you.