Does it matter if the cables cross above the cable guard or below the cable guard?

Some are above, and some are crossed below. It depends on the cams and type of bow. One cable groove of the slide will have a deeper impression; this is for the inside cable when in place. Once you have the cables installed in the slider, they should not be touching each other at the cross-over. The cables should have about 1/8- to 1/4-inch gap between them (this is for waxing and keeping them from rubbing). This should tell you whether the cross-over will rest above or below. This is if the cables where installed by the manufacturer. Look for a picture of your exact bow and see if it matches with what you have set.