Kind 31338 is vastly underspecified. "Audio events" is super generic. An audio message is completely different from a podcast episode and both are even more different than a song. I think it's awful that these things got lumped together in the same NIP.
We will support whichever kind is used for podcasts to provide RSS feeds until apps start fetching from relays directly. I agree podcast is very different from generic "audio" or a "song", because for starters these days it's very often a video...