Why don't pre-chargebacks and refunds made through the Airwallex web-app appear in my Shopify admin account?

If a payment attempt has already been successful, any subsequent change events such as chargebacks will not be synchronised back to Shopify. This is because Shopify does not offer this capability to third-party payment providers. If there are refunds that need to be synchronised in Shopify, please mark the order as "refunded" in Shopify and it will be synchronised accordingly.