I love your commitment to doing it in the original style, and it reminds me of a great week in Süd Tirol, but wouldn't a fringe twister with crocodile clamps be much more efficient? After a few tests it is easy to determine how many turns are needed and you can twist a cord in one tenth of the time without any visible differences.
Mine is home-made and looks like the Ashford twister. I twist a number of times in one direction and 2/3 times with both end held together, in de other.
I did this with the twist and cross method by hand too. But much faster.
Like this: one cord in the right hand, one in the left. You twist both cords simultaneously with your thumbs and index fingers (both in the same direction off course to get a higher twist). Then you change your cords from one hand to the other (so left to right and right to left) in the other direction. With a bit of practice you´ll be much faster.