Another update. I spoke with my friend and one of my accordion repair gurus, Michael Rheinländer of Rheinländer Akkordeon Werkstatt in Cologne, Germany. He has seen many recent Weltmeisters with these worthless, leaky bellows with the fabric corners, so it's not some isolated example. They do not currently make them like this, so if you buy a brand new one, unless it's old stock, you're probably okay. However, if you buy one made just a few years ago that looks exactly like the ones currently being made, you should check the inside bellows corners, lest you wind up with something unplayable.