have you fiddled with the in-game sliders? looks like they are additional multipliers for x- and y-axis.
not sure if it's worth adding support for them, but the notes should probably tell the user to leave them at default.
one big problem is that mouse movement at lower sensitivities gets ignored.
with MouseSensitivity=4.427166 and 1000 DPI it won't let me aim upwards unless i move the mouse pretty quickly.