Kaisirak - the bug in this thread pertains only to triggers in subevents.
So I do not think it applies.
Futher, it does not look like a bug: it seems you're confused about how picking works with families. See 'Picking families in events' in the manual - in your first example, 'skeleton' picks from all instances, not just those with animation 'death' not playing, because the 'Monsters' family picks instances separately. This is by design.