Who's going to supply a list of CI vs. speed for all aircraft then?
For A320 series the normal Mach range for cruise is between .76 and .80, but for ATR for example there's no such thing as CI and the cruise speed is always standard. For Tu-214 for example I have no idea what the speed range could be and so on. .. so using any math to calculate the speed range from the current nominal cruise speed is difficult and will lead to errors. And add the fuel consumption math there ...
But some simplification could work, where you just choose "slow-normal-fast" cruise speed target (not available for props), and system would assume that for example 'fast' is then 1.02x standard speed and 'slow' is 0.98x standard speed (these are from A320 speeds). For fuel usage it's much more complicated though as you need to carry more fuel which in turn needs more fuel etc. (generally speaking CI100/M80 for A320 on a 2.5hr leg needs some 300-400kg more, and CI200 (M80 but lower FL) needs then 600+kg more, with flight time savings being about 3-8 minutes on such leg, depending on winds ...roughly) ...so all in all, there's not much difference in flight times really on shorter legs; adding 0.02 mach (.78->.80) starts to show really on flights longer than 3-3,5hrs.
But another major difference is the climb/descent speed - standard CI20 for A320 series gives about 280-290 in climb (depending on weight/winds) and something between 270-285 in desc (anything below 300kts is a real granny speed ... blah these fuel prices and the resulting economy speeds
).. While CI100 puts 340 kts to both. Again this data for all planes is rather impossible to be sourced from. (and for props again, their climb/cruise/descent speeds are always roughly the same .. in ATR you'd have 170 kts or 190 kts ias climb only and that's it, all other speeds were standard)
However it is true that some flights are planned with a high CI to begin with due to crew rest or scheduling constraints. But in AWS managing that would be difficult - when you think of possible future features like automated conversions of routes between fleet types and so on.
..so to make it short; since the flight time and fuel calculations in AWS are extremely accurate, I'd hate to spoil them with some additions that are not based on any real/proper data, and having such speed range data for all planes isn't really something that's available easily anywhere.