Is this fixed now? It's been a few months!
There's been some further discussion clarifying the confusion:
discountedUnitPrice(Set) is the unit price of the LineItem after line item level discount, but without Order level discount. The field name could be misleading. Since we can't easily change the field name in a public API, I've updated the documentation for the field discountedUnitPriceSet to explicitly call out the fact that it does not include any Order level discounts.
And if merchants want to know the line item after order discount unit price, without intending to use that value to refund the customer, then
discountAllocationsis the way to go. However, merchants still should not use that to issue refunds, as that does not take into consideration any taxes. To refund, use