secondary title could (should?) be localised

The secondary title isn't currently localised. This results in e.g. "Turkic" being in English no matter what language the rest of the interface is in:

I'm not sure localising this is the right way to go, but perhaps in some cases it makes sense. If we were to have a localisation string for it, we could have a default fall-back (as always), so that the decision could be made on a per-language basis.

We'd also have to figure out where to store this localisation, since the secondary title is site-specific, and is stored in the config. It could be as simple as saying which translation string to use (and providing the string for all) instead of defining the string in the config.