CERN isn't a company, but a cross-governmental research organization. I don't think the real CERN knows or cares about the fictional SERN. If anything, they'd probably find it amusing. The show -and the visual novel it's based on- are basically building on the story of "John Titor", which was the pseudonym of person or persons posting online in the early 2000s, claiming to be a time traveler from a future in which CERN invents time travel and takes over the world.