Welcome to the world of aviation where everyone thinks their units are best and only the unit of time seems to be a commonly agreed thing.
Don't worry, once we add more advanced options for fuel or weight and balance you will probably get the option to switch to your preferred unit system.
As long as your fuel burn and your fuel amount is measure with respect to the same units you should have no issue of having a feel for when it's about to run dry since the fuel quantity divided by the fuel burn always yields time in the same unit. In pounds it just uses 2.2x as much fuel looking at each number.
If you asked a physicist they would probably change everything to kg and meter/second in an instant. And most airlines in Europe use kg exclusively, runway lengths are indeed measured in meters over here and probably almost everywhere outside the US and more and more airlines in the US are also changing over to the international standard unit of mass, which is the kilogram.
Since nowadays both the foot and the pound are defined by their SI-unit counter parts these units are mere factors that are there to confuse us
We're using SI units in Aerofly because we never want to worry about units during our calculations.
Why don't you ask the manufacturer and they couldn't stick to the international standard... he he
I guess we're stuck with altitudes in feet and speed in knots, because of the nice separation of 1000ft (305m) between aircraft, nice 250kt/10000ft speed limit (instead of 128m/s, 3048m). China and Russia are indeed using metric altitudes already.