"Today" and "Yesterday" are not using English language by default if javascript is not enabled (for instance with NoScript), see the attached screenshot.
But it was working fine until yesterday.

Heh, it's in czech language.
don't know why, but I feel proud

I know why - I bet it has something to do with some Flaminator...

Quote from Eclipsed :

I know why - I bet it has something to do with some Flaminator...

He should Czech what he's doing a bit more carefully

I am innocent!

Is this still happening?

Russian today with вчера and сегодня.

But it vanishes after I logged in.

Now Dutch with Vandaag and Eergister

I wish mine said that, lol! I've put my languange to Dutch, but it's showing it in English.