This is what I found in https://en.wikipedia.org/wiki/Book_of_Judith
Historicity of Judith
It is generally accepted that the Book of Judith is ahistorical. The fictional nature “is evident from its blending of history and fiction, beginning in the very first verse, and is too prevalent thereafter to be considered as the result of mere historical mistakes.”
Thus, the great villain is “Nebuchadnezzar, who ruled over the Assyrians” (1:1), yet the historical Nebuchadnezzar II was the king of Babylonia. Other details, such as fictional place names, the immense size of armies and fortifications, and the dating of events, cannot be reconciled with the historical record. Judith’s village, Bethulia (literally “virginity”) is unknown and otherwise unattested to in any ancient writing.
Nevertheless, there have been various attempts by both scholars and clergy to understand the characters and events in the Book as allegorical representations of actual personages and historical events. Much of this work has focused on linking Nebuchadnezzar with various conquerors of Judea from different time periods and, more recently, linking Judith herself with historical female leaders, including Queen Salome Alexandra, Judea’s only female monarch (76-67 BCE) and its last ruler to die while Judea remained an independent kingdom.
This site has a lot more information as to this logic: http://www.newadvent.org/cathen/08554a.htm
Catholics with very few exceptions accept the book of Judith as a narrative of facts, not as an allegory. Even Jahn considers that the genealogy of Judith is inexplicable on the hypothesis that the story is a mere fiction (“Introductio”, Vienna, 1814, p. 461). Why carry out the genealogy of a fictitious person through fifteen generations? The Fathers have ever looked upon the book as historical. St. Jerome, who excluded Judith from the Canon, nonetheless accepted the person of the valiant woman as historical (Ep. lxv, 1).
Against this traditional view there are, it must be confessed, very serious difficulties, due, as Calmet insists, to the doubtful and disputed condition of the text. The historical and geographical statements in the book, as we now have it, are difficult to understand: thus
- Nabuchodonosor was apparently never King of Nineveh, for he came to the throne in 605, whereas Nineveh was destroyed certainly not later than 606, and after that the Assyriansceased to exist as a people;
- the allusion in i, 6, to Erioch, King of the Elicians, is suspicious; we are reminded of the Arioch of Genesis 14:1. The Septuagint makes him King of the Elumaens, presumably the Elamites,
- the character of Nabuchodonosor is hardly that portrayed for us on the monuments: in the India House Inscription, for example, his sentiments are remarkable for the modesty of their tone. On the other hand, we must remember that, as Sayce says, the “Assyrian kings were most brazen-faces liars on their monuments”;
- the name Vagao, or the Septuagint Bagoas, for the eunuch of Holofernes is suggestive of the Bagoses, who, according to Josephus (Antiquities, XI, vii, 1), polluted the temple and to whom apparently we have a reference in the recently discovered papyri from Assuan;
- the mixture of Babylonian, Greek, and Persian names in the book should be noted;
- the genealogy of Judith as given in the Vulgate is a medley: that given in the three principal Greek codices is perhaps better but varies in every one. Still it is an historical genealogy, though ill-conserved;
- a geographical puzzle is presented by the Vulgate of ii, 12-16; the Septuagint is much superior, and it should be noted that throughout this version, especially in Codex B, we have the most interesting details furnished us (cf. particularly i, 9; ii, 13, 28-9). The Septuagint also gives us information about Achior which is wanting in the Vulgate; it is apparently hinted in vi, 2, 5, that he was an Ephraimite and a mercenary hired by Moad;
- Bethulia itself is a mystery: according to the Septuagint it was large, had streets and towers (vii, 22, 32), and withstood a long siege at the hands of a vast army. Its position, too, is stated with minuteness; it stood on the edge of the Plain of Esdrelon and guarded the pass to Jerusalem; yet no trace of the existence of such a place is to be found (unless we accept the theory of Conder, “Handbook”, 5th ed., p. 239);
- the names, Judith (Jewess), Achior (brother of light), and Bethulia (?Bethel, i.e. ?Jerusalem, or perhaps from the Hebrew meaning “virgin” — in the shorter Hebrew version Judith is called not “the widow” but “the virgin”, i.e. Bethulia), sound rather like symbolic names than those of historical places or persons;
- in Judith’s speech to Holofernes there is (xi, 12, 15) some apparent confusion between Bethulia and Jerusalem;
- while the events are referred to the time of Nabuchodonosor, and therefore to the close of the Hebrew monarchy, we seem to have in v, 22, and viii, 18-19, an allusion to the time subsequent to the Restoration;
- there is no king in Palestine (iv, 5), but only a high priest, Joachim or Eliachim; and in iv, 8; xi, 14; xv, 8 (Sept.), the Sanhedrin is apparently mentioned;
- the book has a Persian and even a Greek colouring, as is evidenced by the recurrence of such names as Bagoas and Holofernes.