In case of registration form in BSP application, when future supplier completes the registration form, as standard, confirmation page does not shown. This situation may be confused for the supplier that doesn't know if the form was sent correctly or not.
In order to show the confirmation page follow the next steps:
1) Access questionnaire

2) Select Questionnaire and Change

3) Go to "Extras" Menu

4) Select "Yes" Value. and Save.

For more information review SAP Note 1074587 - SURVEY: Confirmation page for BSP application
Hope This Help !