And Hebrews 1:8, is in fact a quotation of Psalms 45:6 which was originally in the Hebrew Language.
The truth is that the term O’ THEOS is not found in the Hebrew Bible also called the Masoretic Text. The O’ THEOS was taken from the Septuagint [LXX], a Greek translation of the Old Testament Even there, according to B.F. wescott
In the Goodspeed and Moffat translations, God the Father is not calling the Son God. Rather, God is telling the Son (Christ) that He (Father) is His (Son's) throne.