Challenge 1: Knitting Flat. I have no idea why our knitting friends in England insist on working traditional stranded colorwork back and forth, in rows. This piece is even referred to as "Fair Isle" by the designer, though I doubt if any traditional knitters on Fair or anywhere in Shetland would claim this as their own. And that's not because the style is modern, though it is. It's because knitting this in 5 flat pieces and then seaming them together would be absolutely miserable. True Fair Isle knitting is worked circularly, by definition.
Challenge 2: Shaping. I suspect that Roan's silhouette is influenced by the Japanese Kimono, with its square drop-shoulder sleeves and continuous neck opening. But there's just one little problem: The shape of this piece doesn't allow us anywhere to put our necks. I've read the directions and checked them twice, and the pattern clearly states that the two front rectangles should meet at the center of the back. Which means there's no notch for the wearer's neck. The fronts, correspondingly, have to hike up at the center, (see photo above: "hold the bucket up higher, honey!") Anatomically speaking, this shape can't properly fit a body.
This is the shape I would make, if I were to knit Roan. The chart and stitch counts will still work perfectly, with just a couple of small changes. I've imagined a few things that would make it friendlier to wear, and much more fun to knit: