Refunds are a little bit tricky for some people because, while it is technically only one order, it's actually two different transactions - the initial purchase transaction and the later refund transaction. Shopify will want to see both transactions connected by the customer or order number in order to properly report both.
When setting up your file for import, the first thing you need to do is mark the financial status as refunded for any refunded orders. This will tell Shopify that this particular order has been refunded. To get the order to show up in your order reports you'll need to add a second transaction line for the refund itself. In other words, the first transaction is for the original payment and the second transaction is for the refunded payment.
If you're working with orders that are refunded and you want them marked as fulfilled, you'll also need to map the fulfillment_status on the Order Details section, which is different than the fulfillment_status on the Line Items section, as it marks the fulfillment status for the entire order rather than just the line item. If you do not map this field when doing a refund, your order will be imported as 'unfulfilled'.
Finally, you'll also want to make sure that the transaction_kind column is reporting the transaction as a 'refund' for the refund line item.
Once you have your data mapping completed with multiple transactions you can now import your order. After the order is successfully imported, log into the Shopify admin and navigate to the order you just imported. The refund amount for the order should now show up in your reports.
We highly recommend testing this with just a few orders before doing your full import to ensure that it looks how you expect in your Shopify Admin panel.
If you have any other questions about transactions please don't hesitate to reach out at support@orderimp.com.