Last night I was unable to login to the forums, when I got redirected to the error page it showed the error in Japanese text when the language was set to English (EN), but when I changed to language to English (NA) from the error page I got the error in English, So I changed it back to English (EN) from the error page again and it showed the error in english.

I would suspect that it is a problem when you are redirected to the error page from the Square Enix account login page.

This error (in Japanese) would occur every time I tried to login.