That bleeder doesn't indicate vented or non vented, ATE or Perrot must have decided it wasn't necessary at some point, like the inside half where there's just one bleeder at the top. What determines a vented caliper is the spacer, otherwise they're the same.
Court the 2 bolts holding the calipers on have 19mm heads but the size of the bolts are M16x1.5 bottom and M14x1.5 at the top, the lengths are the same. The bottom is usually tight because it's a machined fit in the caliper hole, ie 16mm where the shank of the bolt is a true 16mm. Top one has full threaded shank, and is not pre loctited when new, only bottom one.