some rumours which i believe to be true (most of them from official polish site of kingbounty)
1. according to the official kingbounty.pl polish site there will be scenario editor in the expansion
2. according to site gry-online , polish version of expansion will be out in june. So the game is probably translated to some point at the moment, because otherwise there will be not enough time to release it so fast. I think that it is also true for english translation. I am not sure if this rumour is true (gry-online is not an official source), but lets hope for that.
3. check
http://kingsbounty.pl/ - there are some news and rumours in polish , but there are also some screenshots that you may did not see before