In some cases two refund actions can happen in the transaction but none of them is sent to acquirer.

When a refund request fails there's no retry, a CreateTaskAsyncRequest sends an email notification to merchant about the error and a manual refund must be requested to acquirer. In this case the refund is logged with type = email-notification, a successful refund would be online, both should never happen in a normal scenario.

https://.vtexpayments.com.br/api/pvt/transactions//refunds

We were not able to simulate.

Not available, a manual refund must be performed (merchant + acquirer).