serge During indexing Tonfotos reads ‘.piciasa.ini’ files and extracts all the data about people that is stored there. Also, it reads information about people from XMP metadata. Depending on the settings and version, Picasa is capable writing this information to both ini files and/or XMP. However, in your case for some reason it has written only part of the information.
However, just to be on the safe side, we can double check for you, that this is indeed Picasa problem, not Tonfotos problem. Can you please find one file that has more assigned faces in Picasa than in Tonfotos? Can you please open .picasa.ini file in the same directory and check if three is indeed all necessary information about those faces? If you have difficulties understanding ini file structure - share it with us, we can check for you.
If there is indeed Tonfotos issue, we will be more than happy to fix it.