This is not at the top of my wish list given the number of other items that I think takes priority but I think it is nevertheless a nice thing to have at some point in the future.
With the PMDG DC-6 release, I’ve been seing videos of engine start and the transition between different speeds is jarring. You can clearly see when the prop state changes. This feels like a consequence of how the propeller states are defined. The documentation does mention that more states may be defined.
Recently, DCS has completely revamped their prop simulation resulting in the animation of rotating components looking smooth across different speeds without a performance hit. In contrast to propeller state mesh definitions of MSFS, only a single propeller blade is modeled as a 3D object. This allows the simulator itself to render propellers across different speeds with no jarring transitions consistently across all aircraft rather than rely on the developer.
You can see a fan inside the cockpit demonstrating the effect of simulating the rotation of each blade as it smoothly speeds up and down when interrupted in this video.