The Enigma code was not easy to descript. It was extreme difficult.
One of the keys to breaking the code was when one of the decoders over heard two secretaries discussing the fact that one of the German encoders always included, “Heil Hitler” at the end of every message. That was a big help when the British started having success in deciding messages.
By the end of the war, the British were able to decode the messages in real time.
There were two Enigma Machines, one for the army and one for the navy. The naval code was tougher to break than the army code.
The weakness of all substitution ciphers, even clever rolling substitution ciphers like enigma generated, is that similar input produced similar - but not identical output. The similarities being sufficient that with the help of Turing’s “bombe” and very clever language analysts, the code could be broken, and was. The fact that military messaging contained similar text day after day helped the allies break it.
Had the Germans know of modern RSA type encryption, codebreaking wouldn’t have been possible and Alan Turing would have just been famous for all the other genius stuff he did.
The Japanese actually suspected their codes had been broken, but reasoned from a conclusion. Since the codes were unbreakable, they concluded they had been the victims of spies or traitors.