Think that's a typo Snack. Definitely those keys move the designated sensor cursor - i.e. whichever sensor you have selected (in game parlance, Sensor Of Interest or SOI), which includes the Mav seeker, the Targeting pod and/or the cursor on your tactical map display (called TAD) in the left MFD, these keys will move that particular sensor's field of view or the cursor acros the map to select a position.
As for trims, I suspect perhaps the quick manual has a typo and forgotten to put a modifier (shift, Cntrl Alt) as prefix to those contorls but can't be sure; I've changed mine from default to be the keyboard cursor keys. They're defaulted to be used as flight control input, but my opinion is that if you have a joystick, then you don't need the cursor keys to fly the plane!