Has an Eredivisie game ever ended 12-1?
Exactly once. On May 22, 1972, AFC Ajax beat Vitesse 12-1, and no Eredivisie game before or since has ended that way. When it happened it was a scorigami, the first 12-1 in league history.
That makes 12-1 the 40th most common final score out of 48 that have ever occurred in Eredivisie. One point away, 13-1 has happened never and 12-2 has happened never.