The two brass round devices on the left and right side of the brass front visor edge trim piece are rank denotation devices from a shoulder board for beamte or civil service personnel. And the rear visor has brass rounded dome pins as well, at least from what I see in your 2nd from the left photo you posted. Someone played around with this helmet and doctored it up a bit, unfortunately, with these pins.
The right and left side of the brass metal trim on the front visor should have domed split brads.
It looks like rear of the round spike base has had s pin replaced as well. The angle of your photographs does not show the top back area of the helmet to see what the pin looks like on the top of the rear spike base area.
Alan