I found the problem with the
Posti Rimanenti: 14[Massimo9999]
this was a bad translation into Italian of RSVP_REMAINING_SPACES - it was set to
RSVP_REMAINING_SPACES="%s[Massimo9999]"
instead of
RSVP_REMAINING_SPACES="%s[max9999]"
the word 'max' had a mathematical rather than linquisitic meaning. I'll ask
carcam to check with our Italian translator on correcting this for the next release/
For the month view you needed to enable attendee counts in list views (which has a performance impact so it off by default).