Strictly speaking there is no legal obligation to register a warranty with any manufacturer regardless of what legal gobbeldygook they may state in the printed documents.
The fact is that you are warranted for the entire specified period as long as you retain the proof of purchase document (ie. invoice, sales slip etc.)
I wouldn't worry too much about it so try and register again in a few weeks or months once the website is back up.
In the meantime you are fully covered by law.
Gary