Maybe you're right.
I just looked at the french forum and the level difference is not even mentionned, so maybe the only change is the range of the ratio. A simple case of blurry translation
Now, I wonder if the formula is changed only for monsters or for us, too. It would be pretty neat if the damage output skyrocket for those DD with great attack buffs.
By the way, there is another translation problem. The english forum mentions "an enmity reduction by approximately thirty percent" whereas the french one translates an "enmity reduction to 30% of what is was before", so, basically, 70% drop in enmity gain.