Has a World Baseball Classic game ever ended 11-9?
Exactly once. On March 12, 2017, Mexico beat Venezuela 11-9, and no World Baseball Classic game before or since has ended that way. When it happened it was a scorigami, the first 11-9 in league history.
That makes 11-9 the 47th most common final score out of 80 that have ever occurred in World Baseball Classic. One point away, 12-9 has happened never and 11-10 has happened 1 times.