OK so I did some experimenting - the long press of 1 second of the forward/backward steering wheel buttons cycles favorite TuneIn (podcast) stations and changes any audio source (radio, Spotify, slacker, phone bluetooth, to TuneIn and cycles through TuneIn favorites. That's all it does. I have no idea why, but it's been this why on Tesla firmwares (in the US?) for a long time. Not sure if you have TuneIn in Hong Kong (Maybe that's why it does nothing for you?)
I removed the favorite stations I had "starred" (or favorited) in TuneIn so that I had no favorites. Then I tried the long press of these buttons on all audio sources and nothing happens now.
That's a worthwhile tradeoff. I'll just remove TuneIn favorites and now these buttons can work with your kit with no issues (plus hdmi box!).