As far as I have been able to figure out, the jabot's appropriateness in black-tie-equivalent Highland attire is dependant on which region of Scotland one is in or the region of Scotland from which one comes: East vs. West. This seems to be projected on the wearing of the jabot in that situation outside of the Highlands to some degree or another from either side in some of the discussions on the forum. I think the jabot is always an appropriate option in white-tie-equivalent Highland attire.

I'm not Scottish!