Progress! After a very helpful video call with Barb (thank you!) to figure out the pleating, here's a small but helpful tip that worked for me to get a more detailed "preview" of the pleats for pleating to the sett. After identifying the elements according to the TAoK method (or any other), put a pin in the rough pleat centers so you know how many you will get and calculate your pleat size.

Then, don't just mark the pleat centers, but also use pins to mark the correct pleat width at the waist and hip. This helped me a lot to see the symmetry in the pleating, get the pleat size right, correct small incongruences with the pleat centers and test-fold the tartan to see where pleats land and where the taper will have to be.

I will update with pictures when there is more to see. So far, thanks all, and Barb in particular!