Hi,
The settings in voicemail.conf are for asterisk to check the mailboxes, and fire appropriate events to AMI if there is a change.
Those values are all that should be needed to get refreshed numbers on FOP2. You can always start FOP2 in debug mode and inspect the manager events, the mailbox counts, that are returned by Asterisk and see if those are correct or still wrong. If the later, is an asterisk problem.. if the former, and fop2 displays wrong data, is a fop2 problem.
Best regards,