Nice work and very interesting. What is the reason for the twist?
It reduces strain on the wrist and helps reduce the risk of carpal tunnel syndrome.
Violin and mandolin makers started doing it in the 1800’s, classical guitar makers have also done it since the 1970’s or possibly earlier but the most well known example is the Torzal Guitars basses which have a massive 35 degree twist. 15 degrees at the nut for the left hand wrist and 20 degrees in the opposite direction at the bridge for the right hand wrist. If you haven’t seen them take a look. They are totally bonkers.