The scanning order is same as the widgets configured in the CapSense Configurator. Debounce is a software parameter that determines the no of scans the button should have difference counts greater than FT + hysteresis to report ON status. This doesn't affect the scanning which is hardware action. Scanning happens every time you call Scan API in the application.
Assume you are calling the Scan API every 10 ms in the application with n buttons. If you set the debounce parameter to 2, following happens:
Hope this answers your question.