Hello. First I will write the objectives for each race in the Flight map/quest in Disciples 2 Rise of the Elves.

The Legion must bring demon Fareum to five obelisks within the elven lands.
The Elves must reach the Dwarven Altar with four Elven hunters or five must survive 60 turns.
The Dwarves must retrieve a poison and pollute the wells of both enemies.

The objectives are clear right? Well I notice that not really the case with the Dwarves. When I played with Legion on this map I always losing in favor of Dwarves but they did not beat my army nor they get close to my well. They at all do not getting close to me. I used a cheats for reveal the map and what I found out is that the dwarves do not go to "retrieve" the poison. They go straight to Elven well and elves don't look like they are even protecting the well. Dwarves gets to the well and game over. The Dwarves won. My question is does anybody encounter this behavior with AI? Is it bug or mistake in objectives? Unfinished part of the game or AI cheats/is stupid? It was little hilarious when I was watching that action.

I really dislike Rise of the Elves and tend to think that the original game makers of Disciples 2 are not the ones that put out Rise of the Elves.

No, it was made by the same developer and put by those same people. Rise of the Elf in my opinion isn't bad although I think they could work more on tree evolution for elves.