I do not undertand why not work fb button. It's xenforo untouched in this section. Login it's simple: patience. First appears a slow screen on load of AreYouAHuman? pluggin, before register form. After this, you can access to register form.
At bottom of every page, to left side, it's the language changer. Click on Español (Neutro) Tu link.
If you have any problem and want this addon, tell me by charla or conversation.
Salud2