Looking at the pictures, it's possible they measured from the nut rather than the zero fret.
If you are playing noter/drone, VSL should not matter as much. For chording, a half an inch makes a big difference. The same with a buzz on a drone string. If you are not fretting it, who cares? But it might matter if you ever wanted to sell the dulcimer, so if you bought it new, you might want to contact the builder.
Black Mountain makes their own instruments and they do not look like those Roosebecks made overseas.
Dusty T., Northern California
As a musician, you have to keep one foot back in the past and one foot forward into the future.
-- Dizzy Gillespie