Not really, no, because if you have the right model (a book cipher) it seems it shouldn't be so hard to solve. Those Germans just didn't have time.

That suggests to me that this was a fairly niche cipher, that hadn't got much attention from humans, certainly not nearly as much as more famous cryptograms (the zodiac killer's, kryptos, Elgar's, the Voynich manuscript etc.)

In fact I had never heard of this cryptogram.

I don't think this is all that demonstrative of AI power, more than what we already know from coding prowess.

It is, however, a great counterexample to the often heard assertion that short cryptograms can't be decisively solved because they have too many possible solutions.