As the error states, the params for each instance are expected to be an object. try:
x = []
for row in range(value.getRowCount()):
y = {}
cols = ["partnum", "qtyscheduled", "note"]
for i in range(value.getColumnCount()-1):
y[cols[i]] = value.getValueAt(row, i)
x.append(y)
self.props.instances = x
return self.props.instances
Note: I didn’t run this myself, but this will turn your inner list into a dictionary (object), which is the structure expected for each instance’s params.