Saints aren’t infallible. Certainly the quote from Psalm 81 should be taken in its proper conrext.
6 I have said: You are gods and all of you the sons of the most High. 7 But you like men shall die: and shall fall like one of the princes. 8 Arise, O God, judge thou the earth: for thou shalt inherit among all the nations.Obviously the bolded part does not apply to Our Blessed Mother.She is Queen of Angels and of men and of the Church.
In Revelations 12 she is identified as the Queen, crowned with 12 stars, representing the 12 tribes of Israel and the 12 Apostles. These represent the whole Church.
Can you quote any other saint who calls he a goddess? This the sort of title which protestants point to as idolatry.