what does the quote “so let it be said, let it be written” mean?

Sounds like a paraphrase of “So let it be written; so let it be done” which comes from Cecil B. DeMille’s film The Ten Commandments.
Yul Brynner, who plays Pharaoh, makes a decree and seals it, saying “So let it be written; so let it be done.”
Basically means, that’s how it is now. Put it in writing. Set in stone. Done deal.

So Let It Be Said So Let It Be Done

“so let it be said, let it be written” is an unremarkable phrase. Who cares? “So let it be written, so let it be done” is the phrase.

It means that some point in the written page has been questioned, an editor or publisher has checked it and marked it “Stet”, which means, leave it alone, let it stand,it is correct.

When somebody ( especially someone in power.) orders something to be done and done for posterity.