Thanks.
What battleType to use then? The item is a corpse, in the sense that it is the corpse of the creature dead from natural causes.
Also I used the same BT for items linked to MCDs:
- type: STR_CHRYSALIS_CORPSE
size: 0.4
costSell: 20000
weight: 40
bigSprite: 140
floorSprite: 140
invWidth: 2
invHeight: 3
recoveryPoints: 5
battleType: 11 <-----------------
specialType: 31 <----------------
armor: 26
Unlike the bugged item, these items are also used as effective corpses for the units (liked to armor that is).
However, when placed as MCDs, these corpses can exist without begin generated by the death of a corresponding unit. AFAIK from my testing, at the time, this did work and didn't crash the game. Some time passed I have to test again I guess...