The upper chime supports are the higher of the two pieces that hold the chime vertically against the back board. As well as holding the chime, they also hold the coils in place relative to the arms.
Each of the upper chime supports are different. When attached to the back board, the horizontal arms that hold the coils all line up. Since the chimes are all different lengths, the arms that hold the chime must be different lengths to compensate. The arms for the longer chimes rise up above the coil support arms. The arms for the shorter chimes drop below the coil support arms.
When orienting the support on the printer bed, the supports for the longer chimes can be printed in the normal upright orientation. The supports for the shorter chimes need to be rotated 180 degrees so the the arms that would stick down in normal operation would stick up when printed.
It is not recommended that you add supports in your slicer. The upper chime supports are mostly more flexible than the lower supports, so smoothness in the pins is not so critical.
The default 20% infill works well.