You may not see every contact in the widget because CloudSponge only displays contacts that pass through some simple email validation.
This ensures that your application only gets a list of contacts with reasonable looking email addresses.
One common address that is filtered is the Exchange address. These addresses generally follow this format:
/o=ORGANIZATION_NAME/ou=organizational group/cd=RECIPIENTS/cn=username
If you would like all the emails to appear in the widget, you can set an option to override the filtering of these emails. Specifying:
performEmailValidation: false
in the csPageOptions will display every contact with an email address, valid or not.