A different view of this:
People say "sunrise" and "sunset," They do so in error, but they have been taught this since childhood. So, it is understandable that people do.
Truth is: the earth revolves around the sun, and, as such, the sun can not rise or set. The earths rotation causes us to experience "daybreak" and "nightfall."
How does thi apply to the "flat earth" thingy? To believe there is a "sunrise, sunset," one would have to believe the earth was in fact FLAT, and that the sun actually does revolve around the "flat earth."
So, remember, IF you say sunrise or sunset, you are lending credence to the "flat earth" theory!