Cardinity does not send notifications about insufficient funds, but you can use ready-made tools or develop them yourself. The major e-commerce systems can notify merchants about new orders and payments. The detailed information about every transaction can also be found in your Cardinity account.
Here you can find additional resources that may help you in the process and tell you more about payment processing.
If you haven't found answers to your questions here or need any further assistance, don't hesitate to contact us.