Hey yeah I’m the antenna guy. So this is not in fact a CoM module where the chip and the card antenna are coupled wirelessly. This antenna was in fact connected (spot welded) to contacts on the back of the contact interface PCB. Those contacts were also connected to the bare die of the chip with gold wire bonds. They’re very fragile though, which is why they’re in a dollop of resin. It’s possible one of those 4 wide perimeter contacts were the connection points for the antenna. If so then you would be able to connect a new antenna. You’ll have to check under a microscope or at least get better pictures with your phone to see the wire bonds through the light warping effect of the resin.
If you can figure out where to viably connect an antenna, I can help with the calculations. It would really help to have the Taginfo scan to identify the chip, or a more detailed picture of the previous antenna configuration so I could at least guess the inductance