I don't think there is an established method to do such a thing on Wikia. However, there's probably a few other ways to establish a similar system:
If the AbuseFilter is requested (which may be rejected due to the apparent low incidences of vandalism), you might be able to setup a filter only allowing certain users to edit a certain namespace, but I am not certain. I know it is possible to do such a thing for usergroups, however.
It may be possible to setup custom usergroups for this wiki by requesting it, but if I recall– they are phasing out custom usergroups Wikia-wide in favor for the defaults.
You could also utilize MediaWiki:Titleblacklist by setting a rule that prevents editing of the Template namespace. Except that prevents everyone other than sysops from editing them.
The least elegant way may be to simply manually lock high-use templates to autoconfirmed or sysop. If set to sysop, only those with sysop or content-moderator rights may edit them.
You could also outright hide the edit button on template pages using JS or CSS for non-autoconfirmed users. :P It would probably hinder most potential vandals. Not sure if this would be considered a ToU violation however.
Keeping in mind what JoTS said about wikia phasing out custom user groups, while they are still allowed you could request the Editprotected group for the wiki. It allows users with the group to edit sysop protected pages without having admin rights. We have it on the MCPE Wiki.
Thanks for taking such care with your answers. It looks as if there are a couple of different approaches. I'm on my phone at the moment, I'll be back on the PC tomorrow morning and I'll look at the options properly then.