Yep.i have rarely seen a curve ball moving horizontally. most of the times it’s simply a drop ball. rather have a drop ball anyway.
Osterman throws a curve and some other pitchers throw good curves. But, a curve in softball is not a stand alone pitch.
A pitcher has to have a north-south breaking pitch. And it takes time to get good with it.
These young pitchers should be learning either a drop or a "real" rise. After they get a good vertical movement pitch, then they can play around with a curve.