About your only option is to do what Shopify should be doing behind the scenes to honor the API contract: whenever you retrieve an order object from the API, you need to then also retrieve the associated Return object(s) and dig around in them to associate the reverse fulfillment order dispositions to the refund line items and update the restock_to status and restock location if the product has actually been restocked.
One possible twist to this is it looks like the data structure supports splitting the refund reverse fulfillment across multiple locations (e.g. the customer returns qty 2 for a refund, the order refund has one line , but somehow the restocking is qty 1 to two different locations). I’ve haven’t seen that and don’t know a plausible scenario for it to happen, but the reverse fulfillment order data structure does allow for it.