Psalm 2 is quoted word for word, in order, as it appears in the Septuagint in Acts and somewhere else (I forget where off hand).
We, living in a monolingual culture, tend to forget that Palestine was multilingual, even as Palestine is today. Many can switch from English to Hebrew to Arabic without pausing. Multilingual fluency is common in Europe. In Canada they speak French and English. I think Jesus spoke Greek, Aramaic and Hebrew, and maybe Latin. Aramaic was spoken at home, Greek on the street in trade, and Hebrew in the synagogue. Romans stationed in Palestine probably learned Greek but also knew Latin. I think Jesus preached sometimes in Greek and sometimes in Aramaic and it didn’t bother his mutlilingual audience.
The inspiration of the deuteros cannot be proven by citing their quotation in the NT. Paul quotes pagan philosophers and no one considers their work Scripture.
No one is saying a Greek deutero could not have been translated into Hebrew. Its existence in Hebrew in the Dead Sea Scrolls does not prove a Hebrew origin. Or vice versa, for that matter.