I don’t think the scripture is a big deal. I own a NRSV w deuterocanonical books which includes of course Catholic books, but also Orthodox. In this Bible the books not present in Catholic Bibles today are 1 and 2 Esdras( 3 and 4 Esdras in an appendix of the Latin Vulgate) and the Prayer of Mannesseh( which also is in an appendix of the Latin Vulgate. These three writings were traditionally in the Latin Vulgate however were not reaffirmed as scripture at the Council of Trent. However they were put in an appendix to the Vulgate “Lest they perish”. There’s nothing in these books heretical. Interestingly though, Uriel appears in 2 Esdras. Who is not an official archangel in the church, though is normally named in lists of the seven archangels. Actually many paintings in the Vatican depict Uriel ironically. The Gutenberg Bible and early editions of the KJV also include these 3 writings in the apocrypha section alongside the Catholic books. So in my opinion these books aren’t viewed as heretical by the Church in any sense. Just were not given the “inspired writing” status. These books also have status in Eastern Orthodoxy. 1 Esdras is in Orthodox Bibles. The Prayer of Mannesseh appears in the Book of Odes in Orthodox Bibles. 2 Esdras appears in the Slavonic Bible, or Russian Orthodox Bibles.
So the really only true unique books to Orthodoxy that never were received in any sense to the Catholic Church are, as you said, 3 and 4 Maccabees and Psalm 151. The reason they appear is because they were present in the Septuagint, and Orthodox, especially Greek really base their Old Testament off the Septuagint. I have often wondered why 3 and 4 Maccabees didn’t make the Catholic Canon when most of our extra books were books in the Septuagint. None of these texts are heretical to the Catholic Churches teachings in any sense. 3 Maccabees is an interesting read about Jews under Ptolemy Philopater in Egypt, who tried entering the Temple, wasn’t aloud too and then he persecuted the Jews, actually wanting to have drugged elephants stampede them.( may sound ridiculous but this did historically happen at times in antiquity.) In the end the Jewish people through prayer are saved. 4 Maccabees, although very Stoic, really just expands on the story of Eleazor and the 7 sons from 2 Maccabees and is a book about reason over the emotions. Absolutely nothing heretical about it. 3 Maccabees is canon in Orthodoxy. I believe 4 Maccabees appears in an appendix to the Greek Bible.
In the end I don’t think these texts would make or break anything. I think they Church if it meant reunification would even consider adding them to the Canon. That’s just my opinion though.