Here is a summary of issues regarding the numbering of the Books of Ezra/Esdras, and 3 Ezra, and the presence of 4 Maccabees in some Orthodox Bibles.
In the Greek Septuagint, there is Esdras A (1 Esdras) and Esdras B (Ezra-Nehemia combined in terms of what’s familiar from English Bibles based on the Hebrew Masoretic).
1 Esdras (accepted as part of Scripture in the Orthodox Bible) has been characterized as a free-flowing Greek version paralleling 2 Chronicles, Ezra, and Nehemiah, including the “Tale of the Three Guardsmen” in chapters 2-4.
2 Esdras is a direct translation of the single Hebrew book of Ezra-Nehemiah together in one historical sequence.
While these are included in Orthodox Christian Scripture, Catholic and Protestant Bibles reject 1 Esdras and place it in an appendix or omit it entirely, and split 2 Esdras into Ezra and Nehemiah. The apocalyptic text often titled “2 Esdras” in Protestant/Catholic apocrypha, or 4 Esdras in the Vulgate, was not part of the original Greek Septuagint. The Slavonic and Russian Bibles have a 3 Esdra drawn from the Latin Vulgate as an appendix at the end of the Old Testament, following 3 Maccabees.
The 1911 Encyclopedia Britannica explains this: “The titles of the various books of the Ezra literature are very confusing. The Greek, the Old Latin, the Syriac, and the English Bible from 1560 onwards designate… 1 Esdras, the canonical books Ezra and Nehemiah being 2 Esdras in the Greek. In the Vulgate, however, [1 Esdras] was, through the action of Jerome, degraded into the third place and called 3 Esdras, whereas the canonical books Ezra and Nehemiah( were called 1 and 2 Esdras, and the Apocalypse of Ezra 4 Esdras.” In the Old Testament of the Orthodox Study Bible (OSB), an English translation of the Greek Septuagint, there is no 3 Esdra as found in Slavonic and Russian Bibles, which is the apocalyptic text drawn from the early Latin Vulgate.
In the listing of books of the Old Testament in Slavonic and Russian tradition by Metropolitan Anthony of the Russian Church Abroad in the 1920s in his Catechism, the First and Second Books of Ezras (Esdras) and Nehemiah are listed by those titles, but in combination as one numbered book. Then he mentions the Third Book of Ezra separately among prophetic writings of scripture. (In the Orthodox Study Bible, there is 1 Ezra, and 2 Ezra, the latter also listed as just Ezra. Then Nehemiah is listed.) In the appendix volume to his early-modern English translation of the Old Testament Septuagint, the Orthodox scholar Michael Asser includes the books of Ezra (Esdra) as they appear in Slavonic and Russian Bibles–the First, Second, and Third Books of Esdra. He notes that 3 Esdra “is not found in the Hebrew and Greek. The Slavonic and Russian translations were made from the Vulgate …. 3 Esdra is found in the Slavonic Bible as the last Book of the Old Testament, following 3 Maccabees,” as a kind of appendix.
From the 9th century, Latin Bibles separated the Ezra and Nehemiah sections of Ezra-Nehemiah into the first and second books of Ezra. I Esdras, Esdras A, is an alternate Greek version of Ezra, with an additional “tale of the three guardsmen” included. I Esdras, called 3 Esdras in the Vulgate, was called apocryphal by St. Jerome.
The early Latin Vulgate of St. Jerome included only one book of Esdra, but the later Catholic Clementine Vulgate split it into 1-4 Esdras. Protestant writers called 1 and 2 Esdra from the Vulgate Ezra and Nehemiah respectively, while titling 3 and 4 Esdra of the later Vulgate as 1 Esdras and 2 Esdras, which were labeled deuterocanonical or apocrypha in Western Bibles. 4 Esdras was a creation of Medieval Latin manuscripts.
Fr. Michael Pomazansky in his Orthodox Dogmatic Theology notes that 2 Ezra and 3 Ezra are not considered “canonical” books in Orthodoxy, but are included in Orthodox Scripture as among what the Greeks called those books “worthy to be read” in Scripture, given that the list of canonical books of the Old Testament was related to those books in Hebrew. But the Jews in the Middle Ages accepted only a smaller number of Old Testament books in their canon in the later form of the Masoretic Text.
Historically, the Greek Orthodox Church printed 4 Maccabees in their Bibles together with the other Maccabees books, but this did not entail that they officially considered 4 Maccabees “canonical.” More recently, the Greek Church moved it to an appendix.