What if they are just forum mods and not in the moderator user group. Would I just need to create a 2nd user group with just that permission checked and assign that to the forum mods?
The typical approach would be to set the permissions which all moderators (content and global) would have for the Moderating user group and create a Super Moderator user group for global moderators with additional permissions.
Regardless of groups, these are moderator permissions so they are/can be set when you define a moderator. That handles what should be global and what is specific to their forum automatically.