I'm no expert on box office reports etc. but based on what I've seen, it looks like the film grossed somewhere around 230 million worldwide, against a budget of 97 million. Who knows how much went into publicity etc. but that gives Fox 130 million dollars. Even if they spent 100 million on publicity, that's 30 million profit.
How much money does a studio have to make in profit to consider a film "successful?" Covenant may not have been a massive blockbuster, but for the sake of argument, a single investment that produces 30 million dollars of profit would be considered successful by almost any metric. Maybe not compared to movies like the Avengers, but for business minded executives, 30 million (again, just using my random 100 million on publicity argument) is not nothing.