None of the AJAX requests use success callbacks. Instead the interface provides immediate feedback and assumes that the request will succeed. This might be acceptable.
However none of the AJAX requests use failure callbacks either. This means that some time after an AJAX request fails, when the user does a reload of the page in question, things will appear to have moved around unexpectedly.
If an AJAX request fails, the user should be notified, and the intended change should be undone in the interface. Alternatively changes are not visible until the AJAX request succeeds, and a progress indicator is shown while waiting.