The regulation is quite detailed in its specifications, but I have found no rule that the split pins have to be placed in a special position. Maybe due to the position of the upper head split pin of the rear spine, which grips through the flat shallow?
Regarding the holes in the plate fitting, the following is written (dress code for EM‘s from 1903):
….
b) Rear Spine shall be 10.5mm wide and 6mm high, bended to match the shape of the helmet. It grips at the top with a flat shallow under the plate fitting and is attached here by a head split pin, which grips through the flat shallow. Between the air holes in the helmet bomb with a double split pin, and at the bottom of the rear visor with a screw. Above, about 1cm below the plate fitting, an elongated opening that can be closed by a slider (the "ventilation device").
c) The Plate, attached with 4 split pins, has a Diameter of 7,6cm. In the middle a circular cutout in which the attachment is soldered. All around the cutout and around the outer edge of the plate, it has a bulge-like elevation, both rest on the leather of the helmet bomb….