Has a FIBA World Cup game ever ended 84-63?
Exactly once. On February 24, 2019, Senegal beat Nigeria 84-63, and no FIBA World Cup game before or since has ended that way. When it happened it was a scorigami, the first 84-63 in league history.
That makes 84-63 the 475th most common final score out of 1,178 that have ever occurred in FIBA World Cup. One point away, 85-63 has happened 1 times and 84-64 has happened 5 times.