When you look at this from a sewing construction perspective, it is actually pretty tricky. But, Marfy has never designed for the faint of heart.
The front band isn't just inserted into the seam like trim, it is sew to the front before the yoke (and trim) are sewn on. Also, for the front facing I cut the center and inner front, but the top facing (pattern is included) only extends to the edge of the inner front.
But, I did decide to do the topstitching. It looked too boring without it.
I sewed it with emboidery floss by machine. It was tricky to get the tension and stitch length right, and my machine complained loudly every stitch of the way but I'm happy. I sure hope that The Swiss don't hold a grudge, I owe my elna a drink.
I know that it looks tight in the hips and I will let it out, but my hips are simply too big. The back needs support in the form of padding as well as the hips let out. Another thing that sucks about topstitching is that the seams are set once you stitch them.