There's some news.
The map is beatable! And you can gather the required number of skeletons on it!
By the way, I recommend players watch minutes 50-52 of the movie "Scary Movie 2". Those who play the map will understand:)))

I finished the map. It was very fun. I played it as if it were my first month playing Heroes – without scouting, in one go, with one hero, thinking "skeletons are cool, necromancers rule" and all that:)))
I probably won't replay it – the experiment is interesting: what result can a beginner (I really played like someone who just entered a tournament for the first time) achieve without any tricks. People can laugh for a long time about my hero's skills – I really played as if I were on a "hot seat" three weeks after my first acquaintance with the second Heroes game.