I'm pretty sure I've read that people have melted the diaphragm before when trying to attach wires to the pads. I'm not exactly going to test it out myself
Any driver transplants that I've done, I've always left a bit of the original wire attached and just soldered to those.
I mean, it's just a plastic after all. I'm very surprised that it didn't melt anything... or if it did, it was too small to be noticeable.
Kapton my friends, kapton... used for space suits.