Unless it's deeply compelling, believable, or otherwise worthy of performance and audience applause, it really doesn't mean much - at least based on that title.
I'd say that's a pretty weak test. The AI could have repeated the previous phrases for 20 times, and the audience won't be able to tell where exactly to draw the line, but they'll realize that something is wrong.
It's an interesting feat. But it's nowhere near "How Artificial Intelligence Completed Beethoven’s Unfinished Tenth Symphony".
If you wanted to know if they liked the music more, you could play any modern song and it would probably score higher, and I say that as a classical music fan.
To give an example, I would always go to a Mozart concert if the chance comes up, despite me not really liking his music a lot, there’s still no denying that they’re musical masterpieces and provide more than nice sounding tunes.
Fundamentally, current A.I. is predicated on replicating stationary distributions. In that sense they are deeply conservative and can only "predict the past", instead of creating true novelty.
> they have tested it with audiences
What do they do if the audience says that there are too many notes?