See legal fiction. I agree that it's not the word I would have chosen for it: something like "constructed fact" as opposed to "measured fact" seems like a cleaner distinction, but is longer to type.

If you dislike the way Harari abuses terms for myth, you're going to really dislike the way he abuses "religion". His definition is a very reductive "a system of human norms and values that is founded on a belief in a superhuman order". He also has a very reductive, non-theistic sense of Buddhism. He observes that Buddhism is considered a religion, so he overextends his sense of religion until it encompasses all political philosophies

Just as a Buddhist could worship Hindu deities, and just as a monotheist could believe in the existence of Satan, so the typical American nowadays is simultaneously a nationalist (she believes in the existence of an American nation with a special role to play in history), a free-market capitalist (she believes that open competition and the pursuit of self-interest are the best ways to create a prosperous society), and a liberal humanist (she believes that humans have been endowed by their creator with certain inalienable rights). Nationalism will be discussed in Chapter 18. Capitalism – the most successful of the modern religions – gets a whole chapter, Chapter 16, which expounds its principal beliefs and rituals. In the remaining pages of this chapter I will address the humanist religions.

Wittgenstein would kick his ass over these abuses.