I can't answer about what pros hear, but can share some parts of my journey, and some discussions with my teacher over time. There were things I could hear, things I learned to hear, and that learning is ongoing. What you "can hear" presently is not a finite unchanging thing you were born with and that's how it will stay. One part was listening for specific things, doing so from moment to moment. Also, our attention span is much shorter than we think esp. if a thing is new - it might only be a few seconds.
One example was pedal, if you want a particular note to carry over for nuance, or not carry over - the bass note for carrying over. I had to slow down, play that bass note by itself to remember what it sounds like, and then listen for that sound continuing or not. Or I might have an impression of fuzziness, or dryness, or blurriness, whereas my teacher can hear that "the G has cut out early" (thus: get to hear what the G sounds like so I can recognize its presence or absence) In this case I was capable of hearing the G, but had not learned to be attentive.
I was good with note values and counting, but had a poor sense of pulse. I could not hear this so also could not tell I was off. At times that I worked with a metronome and recorded myself, I learned to hear that I was not with the metronome because there was a stutter - but discovered I could not tell whether I was ahead of or behind it: like an ear-dyslexia. Recording in Audacity, I could see what I couldn't hear. The metronome was a spike, piano was a mound, and I could see if the mound was before or after the spike - then listening while watching, started to hear "before" and "after". This helped.
My tendency was to hear melody and to be expressive in a rubato way - my beat would adapt to the melody - whereas musicians who play in orchestras or bands tell me they hear or feel music the other way around. I'd also not hear that I was doing that.
One interesting thing when you start hearing what you couldn't hear before, is that suddenly you hear it everywhere
Gombessa This is the most egregious when I'm trying to control the volume in my left hand, or bring out the melody, or change tempo. I oftentimes THINK I'm making a 40% change, and when I listen to a recording, it actually sounds more like 10% difference.
When you do this, do you play and record the whole piece and then listen? What if you record a couple of lines, then listen back, and do this back and forth? What about going about it in a very exaggerated way and gradually pull back?