There’s bits lots in translation of this pattern. It’s not the easiest to follow…
My numbers don’t add up with the pattern numbers either, but it could be me!
Stitches on needles after short rows 178.
I swapped to size 1 at the armpits as my stitch count was out and my gauge (20 stitches/10cm) too.
Just 6 stitches cast on each underarm.
Body knitted to 32cm length, cast off with 5mm needle. Back looks about an inch shorter than the front.
BOR moved to the side and work joined in the round. 10 short rows added to the back peplum immediately after the increase round. Front and back are now the same length but the front collar is very high. Hopefully the I-cord will pull it down.

Stitches picked but not knitted for the I-cord. 3 rows of I-cord knitted to turn the corner.

Sleeves knitted as size 1.