Hi, does anyone have a script or know about some action to sync the comment set on DHCP static leases to ARP? I would not like to do it manually because it's error-prone.

You can only set comments on static entries.
So that presumes you have entered those ARP entries manually.
Having them set by the DHCP server ("add ARP for leases") does not count, because then the ARP entries are still considered Dynamic even when the lease is static.