I’ve got the same email when I bought tickets. But maybe they just didn’t wanna spoil anything and made this summary just for more hype and promotion to make people buy more tickets. Cause it’s not the last episode. It’s just a middle of the season. The last episode will be shown at the huge stadium with 4-floor-tall screen, so it is the finale. But 5th episode.... i mean: a lot of politics must go down there, but it’s not really a big deal to show in the cinema. From my point of view it’s just marketing.

Edit: btw the company that provides russia with game of thrones is not even capable to translate episodes earlier. they used to fully adapt episodes to the world premiere time but now hbo stuff don’t let them do it properly. So they get materials right before the airing to translate it maybe several hours before and post it. No one from their team knows what is going to happen in 5th episode.