Not sure why the pattern says diagram A should measure 12 cm for the body and 9 cm for the sleeve …?
My row guage is 19 rows = 10 cm. Diagram A is 15 rows so the 9 cm measurement is closer, but still not fight. 15 rows of 1 color stockinette measures 8 cm
Diagram B is 41 rows which gives a yoke depth of ca 22 cm

Body
Knit 31 cm, knit 6 rows short rows to make the back longer than the front, knit diagram A, length 39 cm

Knit 1x1 ribbing at neck with 6 rounds of short rows. Knit 16 cm in length