the Wishlist for Firewall is up-to-date. Wishlists might contain minor things that can configured other way in Zentyal, for example:
* Add support for all the protocols available in /etc/protocols: you can always create by hand the services
* Port forwarding to accept network objects and services: the same, you can create the rules using IPaddr and ports, instead of objects and services
What do you exactly miss in Zentyal firewall? If there is something you really need, you can sponsor features, some partners and customers have made this in the past.
Also if you have Linux knowledge, with the Enterprise support, custom configuration stubs and hooks are covered and our support engineers will help you to configure those on a best effort, no guarantee though as its a feature not present in the product.