I was just thinking that we have no way to distinguish language between the commentary and the picture, as there could be one language in the picture and another in the image.
The idea would be that these new tags would apply to the original commentary, and follow the current rules for language tags, i.e. anything but Japanese. They would all be qualified by the *_commentary addon, e.g. chinese_commentary. Since they describe the commentary, they should also be of the Meta category.
Thoughts?