Well adding more mods to Local boards probably wouldn't help unless they can speak the language. Some child boards probably could do with their own dedicated mods but there's 5 Globals/Admins that can also handle any reports and patrollers can pick up reports from any Newbies which tend to make the most errors or spam.
So why not recruit more mods based on each language 
If language is the key to their impact, we can find more mods based on their language and expertise. I believe that choosing the mod is not difficult for this forum 
Well I'm not in charge of adding more mods and only theymos can do that, but I don't think local boards need more than one, possibly maybe two dedicated mods in some of the bigger locals or if their mod isn't terribly active. Local mods are usually only added to meet demand, so if there's a lot of reports being left in the queue or people start complaining about the lack of action then it's usually looked into but I don't really see any that are calling out for more right now but I don't exactly browse the local boards much so it could be a different story in certain ones.