Encrypted External Drive Using Apple's Password Generator and Forgot the Password: Can It Be Salvaged?

I have a partition on an external HD with some Time Machine backups. I decided to encrypt the partition using Finder and used Apple's built-in password generator to create the passphrase.

Unfortunately, after copying the password for saving in my password manager and after having already accepted the generated password to start the encryption process, I accidentally copied something else! With no clipboard history tool installed, I lost the password.

My question is the following: Is there any way I can salvage the password or partition contents?

Currently, I have access to the contents of the drive. I'm copying/pasting them to another partition, but I have reason to believe that it won't work since it's a Time Machine backup and copying/pasting those is problematic. I can't access the volume through Disk Utility for a restore since it's in the middle of the encryption process.

Is the generated password automatically stored in the Keychain? Is there any way I can cancel the encryption process or decrypt the volume since I have access to its contents?

Any help is appreciated!