Has a World Baseball Classic game ever ended 17-7?
Exactly once. On March 8, 2009, Australia beat Mexico 17-7, and no World Baseball Classic game before or since has ended that way. When it happened it was a scorigami, the first 17-7 in league history.
That makes 17-7 the 47th most common final score out of 80 that have ever occurred in World Baseball Classic. One point away, 18-7 has happened never and 17-8 has happened never.