Feature request: Support for Comment karma value?

I’d recommend writing an extension to the core comments model.

The other option (not as elegant) is to filter the json_api_encode hook. From there you can first check the type of request being done in the $data parameter (ie $data[‘json’] = ‘get_comments’) then you can simply add your data for comment karma, then return the filtered value to the JSON API.

I’m pretty sure adding this type of plugin specific code is outside the scope of this plugin.