On a second thought, we've likely spread the story even further. Yi-Ti also gets a few issues, each month, so the Azure Emperor and the Orange Emperor of Yi-Ti have just learned that there is a woman called Cersei Lannister in Westero that fucks her brother. Same in the planes! I'm betting that the Sultan of Amun Kelisk and the Sultana of the Peerless Empire are likewise reading the Times to keep an eye on what we are up to. They too will now know the name Cersei Lannister, solely for the story how she had her whore-mongering husband killed so that she can get it by her brother.
There are major religions who are less widely known then her now!