Black gave away the win

Game no. 1831608 was won by white by +0.5 points. However, LG's counting algorithm does not track down false eyes. Black has a forcing move at E1, to which White must fill B1, which should shift the result to +0.5 for black. (I hope I did not miss something. Just got home from a long train ride...)

Before black gave away the win, it seems he tried to steal it with the first score count: "Black win by 53.5 points."

But white caught that.

And yes, I think you're right... black should have played at E1.

You're right. Black should have played E1, forcing white to play B1. That's why it's important to play out all the dame points, even under Japanese scoring. Sometimes playing a dame would force your opponent to play a protective move inside his own territory, reducing his score by 1. A point here and there matters in a very close game.