That >>530613038 was the first leak about a Japan X Soviet event in february but there is no really any source about the text or the picture.
The leak also came with a strange picture of Japanese Tiger (strange because it's an event vehicle but also cost 2500 gold).
That >>530613038 was just someone asking for Manchuria campaign in the forum: https://forum.enlisted.net/en/t/august-storm-soviet-japan-new-style-campaign-pack-concept/140929/1