Hanging chandelier with wire support
Beautiful tin ceiling!

It's hard to tell from the pic, but I'd imagine that the rods hanging down from the gold-colored mounting plate are threaded and that they go through the holes on the canopy. If that's the case, then the acorn nuts being tightened against the canopy should be sufficient to hold this up.

Even if the center threaded rod was long enough to thread through the center of the mounting plate, all the weight of the chandelier would be on that gold plate.
With the canopy mounting screws taking the weight, the weight is still borne by that plate, but it is taken in two places instead of one, and the two spots are closer to the edge of the plate instead of in the center. This gives the weight a much shorter lever arm to attempt to bend things, thus making it more difficult.

About the only change I'd make would be to rotate the mounting plate clockwise a bit so that the support bolts are as close as reasonably possible to the screws that hold the plate to the box (i.e. you still have to get a screwdriver on there to tighten the plate to the box).