Line 14 should read: moss 5(9:13) k3p4 c4b twice, p4 k3 p2 t3f p3 c4f p4 c4f p3 t3b p2, to again, moss 5(9:13). The two p3s are the problem.

I think there is also an error on the sleeve section. The pattern for size 3 says to cast on 39 stitches then after the moss section, increase to 44 stitches. Then change needles to size US3 and start the pattern. The first pattern row equals 48 stitches. The pattern doesn’t tell you how to get from the 44 to 48 stitches.

I agree there is an error in the sleeve for size 3. Here’s how I’ve corrected it:

With smaller needles and contrast yarn, cast on 43 st. Change to main color and work rows 1-10 as for welt.
Row 11: Moss 11inc, moss 4 4 times, moss 11. 48 st. (you just need to cast on 4 more st initially and adjust the increase row).