Great report but the photograph accompanied by “This was some interesting rock formation near where I suspect the trailhead for the hard hike to Eas a’ Chual Aluinn was” is about a quarter of a mile north of the start of the walk in to Eas a’ Chual Aluinn. We always comment on this feature when we drive past it (which is about 10 times a year, Assynt being our favourite area!)calling it “the canyon”. The burn which runs through the canyon comes from Loch na Gainmhich and itself forms an impressive fall where it flows over a horizontal slab of pipe rock at the exit from the loch before dropping vertically into the gorge. I’ll try to get a photo of it on our next trip but given the vertical nature of the drop and the precipitous sides, it’s a potentially dangerous location. I suspect the way to do it would be by walking/scrambling up the gorge from the location of your photo to reach the base of the fall althought never having done it, I don’t know how possible this is.