"The model used “TRUPPENVERSCHIEBUNG” as the encryption word, as described on pgs. 214-215 of J. Rives Childs's “The History and Principles of German Military Ciphers, 1914–1918”"

Even if it isn't a simple substitution cipher as you said, all the model did was try a decryption key that had already been found and was publicly accessible. This is basically a nothingburger.