Based on what i know about fireworks , all these bombs have 1 sfondo because sfondo is when the main shell explode.
You can see a 3 sfondi in the video of TURI2007 - Fratelli Romano at the time 9:10. Let's see and you'll can count the 3 sfondi!! :blink1:
The shells of Romano you refer to are indeed "fermate a 3 sfondi". These "fermate" consist of three layers ("solai"). Each layer is a "sfondo" that contains several "intrecci". You can clearly see the break of each "sfondo" because of the orange flame.
However, the "bombe da tiro" have also multiple "sfondi". It is not necessary for a "sfondo" to contain "intrecci" and show the orange flame. A "sfondo" can also be a "contrabomba". Because of the colours (and the flash-break) you do not see an orange flame.
For example, they fired an "8-sfondi bomba da tiro" of which the first sfondo gave two "intrecci" and the following 7 "sfondi" were all "contrabombe". The "contrabombe" are very big and their individual fuses are not lit simultaneously by the fire of the first "sfondo". Each "contrabomba" is given fire by the previous one.
Another example is given with this picture. It is a shell with 4 "sfondi" and a "controcolpo".