We do use the 1st tech all the time, we use it whenever we notice something we didn't. It's the secret sense. A Shishigui assassin, the near imperceptible sound of drumbeats, anything that's hard to notice. That's what makes it so good, because it doesn't demand we actually use sight, we can use it with sight or hearing or anything and if it was twice as good as one of those things at the cost of the other it'd be less for it. I'm okay with hearing taking precedent over sight but we need something thematically specialized but mechanically general, and hearing is the opposite of that. It's a cool quirk with no depth behind it.
The perception types as Xin described then aren't abstract concepts, Clairvoyance is perceiving things, Postcognition is inspecting things for clues to their history and Precognition is taking understanding of things around you and just predicting how they'll act in the future. We can do all these things as mortals in the order of difficulty Xin described, Ling Qi can just become supernaturally good at it. Postcognition as I understand it means looking at the Qi of an object and realizing some of that Qi is perceptibly more recent than others, fading like memories do, and divining that the concepts of Qi reads like a poem of its history.
I mean, if you want to take apart the 3rd tech for points to improve the 1st tech, then sure, I'd be fine with it.
Hearing is more than just a quirk, since the aim is to make it work with music. Music is currently our best skill and *by far* better than the projection skill we currently use for the art. Narratively, it could leaverage the fact that for Ling Qi, music is not just sound and vibration. She basically sings to other people's souls, so couldnt music perception work by listening to the melody of other people or spirits souls for example? Like, there is a lot of potential in Ling Qi's insight into the nature of music that we can work with.
Part of the setting is that the world resists having its laws bent too much. It seems to be fairly flexible with some of them, but Time was mentioned before as a prime example for something that can trigger this reaction.(it was mentioned in the Stepping beyond the 3rd realm informational) Xin mentioned that looking back a bit is still fairly doable, which seems to imply that looking far into the past is actually getting hard, which would fit to the idea of the world trying to resist the attempt. The same principle but worse seems to apply to precognition: Xin mentioned that even she, a 7th realm spirit that is good with divinations, can only peer into the future for about a minute
Peering forward a second or two into your immediate surroundings involves a mere few million relevant factors after all. I might manage as much as a minute, barring interference.