u are evaluating curve as entire joined* curve
crv.getSubObjects() will split into segments on which o can do checks

var curves = moi.geometryDatabase.getSelectedObjects().getCurves();
for (var i = 0; i < curves.length; ++i) {
for (var j = 0; j <= curves.item(i).getSubObjects().length; ++j) {
if ( curves.item(i).getSubObjects().item(j).isCircle || curves.item(i).getSubObjects().item(j).isArc)
// do smt
}
}

http://moi3d.com/forum/messages.php?webtag=MOI&msg=8010.8&highlight=yes and example