not everyone is familiar with traditional Highland attire and some might perceive the black bowtie as an unintended faux pas rather than proper for wear with the kilt.

And while the tie ought to be white, I have seen it done and have no qualms with wearing a black waistcoat with a white bowtie, suitable jacket, and kilt at white tie events.
Could someone please enlighten me on this - were traditional Highland crofters familiar with white tie and black tie events?! : )