>Given that the names were made-up and unique, and have zero hits on google

You said it yourself. I just don't see the novelty that a machine learning algorithm, trained on huge amounts of stuff scraped off the internet, can find rhyming words.

That aside, there's an enormous amount of poetry in the training set. Given the relatively strict constraints of the style, there's not much interesting about slotting in words that grammatically make sense.