Row 6, a WS row, of sleeve pattern should be purl.
Mods: Yarn substitution making things interesting. One is fingering and other is sport. Settled on #5 needle for garter hem and body. Gauge is around 5.5 sts/in. I didn’t want as wide an A shape so I cast on 324 sts and made my decreases every fourth row until I reached stitch count for second smallest size, aiming for a 40in bust giving me 2-3 inches of ease.

Since I am using Kauni, I wanted to modify the sleeves so that the rainbow would flow over the shoulders. The pattern has you knit the back first. This is actually my front which doesn’t matter because the instructions are interchangeable/reversible. Instead of putting my sleeve stitches on hold and picking up for the other side, i knit one ridge three stitches longer than the last on both sleeves before putting the neck stitches on hold and reversing the pattern to knit the sleeve instructions for what is my back from the top of the shoulders down. Once I got to the end I finished with one row of the grey and was left to Kitchener all of my stitches together for the sleeves and across the back. It took a while but was well worth the effort.

A few things I noticed: the final C2 body row should also be your final arm sleeve increase row before moving to instructions for the back. When purling that first row after the provisional cast on, the p2tog serves to eliminate the seam stitch from the body.