I'm not entirely sure if it's a bug, but I created an item with six different targetHitEffectBuff effects, each limited to a different taxon, and notably only the last one was triggering. (I had them all set to 100% and also stuck copies of the abilities they were supposed to trigger in my skill tree so I could cast them like spells so the breakdown in what I was hoping would happen appeared to be that these effects weren't triggering.) I'm also fairly sure I've seen items with multiple hit buffs? So. If this is a bug then it's not just effecting me.
You'll have to make it trigger one effect and then have that effect trigger all this stuff. Items and skills can only have one trigger of the same "type" working.