Hello Adriano,
The reason that Balli isn't included on Jan Safarik's site is probalby that his claim was only for a damaged not a destroyed. The last night-fighter claim for a destroyed (and last Italian claim with the CR.42) was made on the night of 20-21/11-42 by Capitano Scaglierini
http://surfcity.kund.dalnet.se/italy_scaglierini.htm .
Unfortunately I don't have any info on which Gruppo Balli served, only the Stormo. Perhaps Ludovico have more info when he is back on-line after a major computer break-down.
Best wishes/Håkan
BTW. The link to my site is
http://surfcity.kund.dalnet.se