I know nothing of the 'blackface' stunt other than stuff i have read here in this forum.
I don't recall where I first heard of the incident where a white stuntman was put into "blackface" makeup to double for Terrell, but my friends and I certainly shocked Paul Winfield (in Australia, long before the theatrical release of ST II) by knowing about it. He was stunned
that the rumour had made it all the way Down Under, and he confirmed that it was true.
Supposedly, the idea of Terrell tumbling was unscripted/impromptu, which I guess is why no African American stunt man was put onto the day's callsheet. It could
be that no footage was actually shot. The incident threatened to cause a kerfuffle at the then-Stunt Actors Union.