The burst limit is calculated based on the request rate to App42 for an app in a small window. When an app hits the burst limit, any requests over the limit are rejected with 503 error code. So that developer can handle easily on the client side.
If you think your app required the burst limit more than 40 than I will suggest you to post your query on email@example.com. They will help you out in details. Let me know if you need any help from my side.
I will be happy to assist!!!