LS mate just spoke to someone from SE on the phone with EU tech support.
They told them not to expect to be able to register any time today. Apparently they are in fact not doing any maintenance on it, that's just a lie from SE. It's just mass volume of users trying to register still.
They were told to not even bother trying to register until tomorrow, and it won't be fixed any time soon. I guess the "maintenance" news was just to try and stop people spamming retry.