1. Better support for those with hearing impairment - this needs to be done otherwise FD are being notionally "illegally" prejudicial against those players with hearing impairment. The main issue would be resolved by adding a visualisation of the audio component that is allegedly learnable
I hardly notice the sound. I scan the frequencies by reference to where the planet is in the system and what frequencies still remain to be resolved. I don't use the oddly shaped cursors either (other than to point directions). To my mind, if you need either of those then you will have significantly more trouble than I have, which might be mitigated by changing your control scheme.
2. Better support for VR users - the current implementation is abysmal in VR, this could be addressed at least in part by integrating the FSS with the cockpit
The only people who have said that they used VR have said that it isn't that bad but could be better. That's not abysmal. On the other hand, I imagine it would be great if the whole thing was rendered on the inside of a sphere.
3. QOL interface changes such as FSS tuning memory - it is ridiculous that this was not a thing at release and breeches best design practices
I'm not sure what you mean by this, but I think it can be defeated by mapping the tuning to your throttle or another slider. Admittedly, game-pad users miss out on that at least as regards a slider that stays put. I have a dedicated кnob so of course it remembers where it was between scans, but the throttle is a good alternative if it's stable enough. (My joystick cost £18 -- the throttle jumps around a bit too much.)
4. Remove the mini-game feel from both the FSS and DSS - remove par scores, and better integrate the solutions with the cockpit
Does this apply to the station menu as well? It's definitely taking place in the pilot's seat because you can access the side panels.
I agree that the FSS could do without the hazy blue overlay, and the blue planet overlay in the DSS is intrusive and gets in the way. The par score for the DSS gives you an idea of the size of the planet and the probe pattern you should use. I don't see any reason to give a bonus for beating it though, especially as doing so generally means that you haven't really scanned the whole planet.
At the risk of teaching my grandmother to suck eggs, if you haven't already tried this and if you are using a HOTAS, try binding the tuning to the throttle (in absolute mode, not velocity mode if that's an option), the cursor movement to the mouse, zoom in to left click and zoom out to right click.