Following up here on our status - we actually ended up switching off of flow. It was very much a challenge to implement this specific logic and I felt it was unreliable for what we needed which was crucial for our shipment flow. I ended up writing a very basic script in windmill.dev that listened to a shopify order webhook, calculated the right tag, then used the graphql api to modify the tag for a given input order id. It works like a charm and was very inexpensive!! I think this product needs a lot more love and documentation.