First of all, this sheet is amazing. Thank you so much for this.
I have run into a problem regarding air move. B18 says "You can increase air Move directly for 2 points per yard/second, or reduce it for -2 points per yard/second." and B56 says the same "Your flight Move is Basic Speed x2 (drop all fractions). As explained in Move in Other Environments (p. 18), you can adjust this for ±2 points per ±1 yard/second."
This works on the sheet for positive values/increases, but when dealing with decreases, the modifier has no effect, and the point cost will erase any negative value.
Hopefully should be clear from the text, but here are some screenshots
Edit: I should have mentioned, in the screenshots below the basic speed on the sheet is "5.25", so the default for air move is "10"
Below: The modifier is not working for negative values and the point cost is working for positive values. (should be 9 instead of 11)

Below: Neither the modifier or the point cost are working for negative values. (should be 8 instead of 10, also it can't be shown in a picture but negative values can't be entered into the point cost field)

Below: The modifier and point cost are working for positive values. (13 as it should be)

Again, Thanks!