Yes, you can turn the keyboard typing sounds off by doing the following.
Exit kiosk mode by tapping all four corners in a clockwise fashion, starting with the top left. Enter the password 8026. This will close the kiosk application and bring you to the windows login page.
Slide up on the screen to bring open the login prompt, and click on XTL Admin user. Enter in password XTLKiosk80! and hit enter to log in.
Tap on the Windows Startup Menu icon on the bottom left of the screen
Tap on Settings > System > Devices
Under 'Touch Keyboard', tap on 'Play Key Sounds as I Type' to toggle OFF
Another place to check is on the bottom right of the home screen - press the arrow and hold down the icon that looks like a finger, then uncheck the beep option.
*Restart the kiosk to apply all changes. It will bring you back to the Kiosk login page.