I removed IK and rotated the animation by 90 degrees; you can't change the coordinate system of the original gr2 Nival skeleton that you imported into 3DS MAX, otherwise, it will be a mess. I created a movement animation for the ballista in the mask, and after the very first test, I had to redo it.
By the way, footman wanted to know if you have any universal way to adapt animations for Heroes 5. That is, are there any universal values for the distance to move the model and the length of the frames? Or does it always require improvisation and adaptation?