What is the point of decoding this back into the user's original "ENIGMA" and "AMAZON" strings? In this case, "sh(/J3HqAfQsu..u.rqf" is the user's password. If you have that, there is nothing to crack.

Edit: I see "Combine with another compromised password, and we're coming dangerously close to being able to generate a password for any arbitrary website.", which means that if an attacker could obtain a couple of these passwords, they could determine (a lot of) your qwertycard and gain access to more of your accounts.

However, by the time an attacker has any of your passwords, I'm not sure that reverse engineering your qwertycard is an issue. As others put better than I, this would also mean that in addition to obtaining one or more plaintext passwords, the attacker would have to be targeting you specifically and know how you generated the passwords.