That stranger girl

This is an interesting piece, I love the darkness that it itself evokes.

Why has that girl come back
with such so horrible track?

^^
I think the 'so' doesn't belong here.

I wonder! How was she?
A harbinger of banshee
When she commits the blunder,
it sounds like bombing thunder
She's so deft in plagiarism
into any stranger organism
Would she have come to slay
or she'd get dude to stay
Collecting my old wounds
as a slain who has no sounds,

^^
'this last line doesn't really make sense to me, I can understand what you're trying to produce, but it's not really working. Consider changing 'slain' to something else, perhaps. I think that's the word that's putting it off. Here it sounds as though it's used as noun when it shouldn't be.

I would never be pessimistic,
but I'd rather be optimistic

^^
I like this ending. It brings on different emotions - fear, but also a calm, somewhat a resolution to the story you have told.

Great work! 5/5