Holy shit. First, I agree bugs need fixing, like the b12 1+2 string, d1 whiffing, f12 not always connecting properly, and whatever else.
But that's it. The rest of your post is dumb shit. If you play piercing because you think "piercing is pretty much the only Mileena variation that matters competitively," you are wrong, plain and simple. Piercing is shit, ethereal is shit. Ravenous is her only decent variation.
I'll add more to this post detailing why after I get off work. I don't feel like wasting my valuable lunch break typing this shit up.
The correct buffs for ravenous mileena:
-fix the bugs listed above
-increase advantage on hit for high pounce
end of list.