Thanks for the advice, Goanna, but no dice yet.
The files were already present when I checked - clicked Play, nothing.
I decided, just to make sure, to try what you did and so deleted them, followed by a cache integrity check, which said 23 files were missing. After everything was redownloaded, I tried again but the song remains the same - few seconds, nothing happens, and that's it.
Again, just to make sure, I'm running (or failing to run) the Russian version, physical copy. I don't think it'd make much of a difference in the normal run of things, but this particular release wasn't the normal run of things (although for flight sim standards, it wasn't too unusual
) so it might as well be a bug found only on this particular version.
OT: The marketing done in antecipation was quite nice. I jumped into a store in a mall today, shopping for CDs (if anyone's interested, got myself a copy of Radiohead's The King of Limbs, brilliant) and, as I walk in, I see this huge clock with the Cliffs of Dover cover on it, showing 00:00:00 - I didn't get the chance to see it ticking, but it's quite nice to see that there was such antecipation for a release that's considered to be aimed at a "small niche". Sadly it wasn't released under ideal conditions, but hey, there's time to make it an all-time classic, and even the current videos and screenshots hint that it's there already.