I don't recall Veloce Cranks having bolt covers that screw in. As I recall.....they just had pieces of plastic around the allen head crank arm bolt. Centaur had a little nicer allen head crank arm bolt that completely filled the hole. The Centaur ones would work on a Veloce crank arm.
Like this...except the Veloce may have had plastic around the bolt, where Centaur and up was metal.
https://www.ebay.com/itm/CAMPAGNOLO-...Rpn:rk:25:pf:0
I have 4 cranksets with these bolts.