Nothing here requires that the qualitative properties be instantiated in the actual world. In fact, nothing really requires that such properties exist even as universals or as categories. What matters is there seem to be such qualities, and we represent objects as having those qualities. (In philosophers’ language, we could represent the qualities de dicto rather than de re: that is, we could represent that objects have primitive qualities, even if there are no primitive qualities such that we represent objects as having them). In the words of Richard Hall (2007), experienced colors may be dummy properties, introduced to make the work of perception more straightforward. It is easy enough to come up with a computational system of color representation that works just this way, introducing a representational system that encodes qualities along an R-G axis, a B-Y axis, and a brightness axis. Because these axes are represented independently of other physical dimensions such as spatial dimensions, the corresponding qualities seem irreducible to physical qualities.
Something like this is plausibly at least part of the solution to the meta-problem of color. We represent primitive colors as a useful model of complex physical properties (such as reflectance properties) in our environment. Even if no such primitive colors are instantiated in our environment, the mere representation of apparently primitive properties suffices to explain their apparent irreducibility.
This idea can be extended to the meta-problem of consciousness by saying that introspection attributes primitive qualities to mental states for similar reasons. It needs to keep track of similarities and differences in mental states, but doing so directly would be inefficient, and it does not have access to underlying physical states. So it introduces a novel representational system that encodes mental states as having special qualities. Because these qualities are represented independently of other physical dimensions such as spatial dimensions, the corresponding qualities seem irreducible to physical properties.
This proposal works especially well on a view where phenomenal properties are (or seem to be) simple “qualia”. Such a view might have the resources for explaining why our problem intuitions differ from our intuitions about belief: sensory states are represented as simple qualities, while beliefs are represented as relations to complex contents (the cat is on the mat) that do not require a novel space of qualities. However, the qualia view is widely rejected these days, even as an account of how experiences seem to us introspectively. It is much more common to hold that experiences are (or seem to be) representational or relational states. For example, the experience of greenness does not involve a simple “green” quality, but instead seems to involve awareness of greenness, the color. Here greenness is the same quality already used to represent external objects in perceptual representations, and awareness is a mental relation, understood as some sort of representation (on a representationalist view) or some sort of perception (on a relational view). On a view like this, it is unclear how a novel space of primitive qualities attributed in introspection will enter the picture.