I'm trying REALLY hard to read through a lot of the text in act III, but it contains so many double negatives that the characters are contradicting themselves repeatedly.

Was this game translated to English from another language?
Will there be a patch to correct the dialogue so that it makes a modicum of sense?

Example, which has a spoiler:

<spoiler>
At 6 bears camp, after headbutting the chief
"I don't owe to them. Nothing. And never. I don't want to see them never again."
</spoiler>

Owlcat Games is a Russian company.

What character is speaking that quote?

Perhaps the RP character or NPC is bad at grammar? (like me)

In Russian the meaning is slightly different :

"Не хочу быть им должна. Ничего. Никогда. Вообще их больше видеть не хочу."

It should be translated as :

"I don't want to owe them anything. Never ever... I don't want to see them ever again."

Besides grammar error, the translator missed the "want to" part.

I have seen other Amiri grammar mistakes and I believe it was intentional as she is a barbarian.

They're a Russian company but many of the writers are American, or at least from somewhere that speaks English as a first language. I'm pretty sure the barbarians speak in stilted Engligh (or common or whatever fantasy equilivant is in the Pathfinder universe) on purpose, since Amiri and the other barbarians are the only ones who have those kinds of "mistakes". The only other mistakes I've seen are typos and missing text.