There happen to be two versions of the Greek text for the book of Daniel (Old Greek & Theodotion) , and the NETS project has graciously provided side-by-side English translations of both.
The NETS preface to the book of Daniel says this about chapters 4-6:
A detailed comparison of the Greek texts in Daniel 4–6 reveals that less than 19% of any of the vocabulary of TH agrees with the OG. However, when the vocabulary is similar, about 83% of it is exact. Agreements are so few that it is clear that TH is not a revision of the OG in these chapters. At the same
time, given the high percentage of verbatim agreements despite the low frequency of shared readings overall, the only reasonable explanation is that the majority of these agreements are due to textual corruption of the OG with TH readings. Indeed, numerous passages can be isolated where there are double translations in the OG that include the reading of TH.
The fact that in places the OG has both its own reading and the TH reading, suggests to me that the OG is similar to our modern versions of Greek texts that have alternatives bracketed alongside the version's preferred variation. The TH, it would appear, has rationalised the OG text, and among other things, has dropped the additional material.
So, which text is right?
For me, if there is a choice, then a passage that produces inconsistencies should be discarded in favour of the one that doesn't. That's not to say one text should be held superior to the other, but that when a problem arises choose the text that resolves it. Why would anyone choose in favour of inconsistencies?
Having said that, the Theodotion version of Daniel 5:30-31 has this ...
30In that very night Baltasar, the Chaldean king, was killed. 31(6.1)And Darius the Mede received the kingdom, being sixty-two years old.
..., which is pretty-much what is found in the Hebrew. However, the Old Greek version has this:
30And the meaning 1 came upon Baltasar the king, and the rule was taken away from the Chaldeans and was given to the Medes and to the Persians, 31(6.1)and Xerxes, who was king of the Medes, received the kingdom.
So, the OG doesn't declare Belshazzar died on the same night that Daniel was honoured by him for interpreting the writing on the wall. Thus the contradiction disappears.
Someone might argue that the OG differs from the MT (Masoretic Text), so it should be discarded for that reason. But the OG is much older than the MT, and since the sense of the MT is the same as the TH, then the TH is likely the source of the MT.
Again, asserting the superiority of the TH/MT over the OG as far as this passage is concerned, is choosing in favour of inconsistency. Why would anyone do so?
There is no contradiction if one takes the very hermeneutic approach of making use of all the data available for interpreting a text.
- NETS has rendered the Greek τὸ σύγκριμα as "the meaning", but according to the Koine Greek Lexicon, σύγκριμα can mean "judgment/decree". So, given the context, a better translation of the Greek would be, "And judgment came upon Baltasar the king ..."