I've tried a few minutes ago to claim the Cannon Tower skin scraps at my TW account and it worked!. There you have a short video from my Instagram while I'm unlocking the skin for the tower. Don't mind the "super cute", please.
Remember you need to use the following page and code for this purpose, but always selecting the Language of the server (TW server this time). If you don't have an account at TW server, wait until the update be released on your own server.