Hi Jeffro,
What you're asserting is circular reasoning, based on the assumption that verses 6 to 23 are parenthetical.
And your assumption that Ezra attributed different names to Cambyses and Bardiya isn't circular?
If you're applying Ezra 4:12 to Artaxerxes I, then the arrival of Jews "from you to us" would best fit the timing of Ezra and others going to Jerusalem in the 7th year Artaxerxes I, which would require that the order to halt building would follow that. But that would plainly contradict the fact that Ezra had gone to Jerusalem after Artaxerxes I had given Ezra a letter specifically supporting them.
It would be odd for Ezra 4:12 to refer to Jews who arrived in Jerusalem over 70 years prior (from return of Jews in 538BCE until in or after the accession year of Artaxerxes I, 465 BCE), as would be the case if it is said to refer to some time prior to Ezra going to Jerusalem but during the reign of Artaxerxes.
Wait. Artaxerxes was supporting the Jews' worship and their God by donating precious metals, goods, the means to procure animals for sacrifice, etc., to the temple, as well as enabling them to govern the people based on their religious set-up. The Persians not only were tolerant of other religions but, by honoring other people's gods, they ensured divine favor for themselves:
(Ezra 7:23) . . .Let everything that is ordered by the God of the heavens be done with zeal for the house of the God of the heavens, so that there may be no wrath against the king’s realm and his sons.
The letters to and from Artaxerxes in Ezra 4 are undated, but there is no contradiction with it being after Art's 7th year. It's one thing to support the Jews' religious practices; it's another to tolerate the rebuilding of a fortified city which could be used to break away and become independent from Persia - especially with Jerusalem's history of attempted rebellions (see 4:13-16). So Art. stipulated that no more building should be done until he ordered it (4:21).
The book of Esther presents Xerxes I as favourable toward the Jews, with no indication that he was the 'Ahasuerus' who prevented construction in Jerusalem either.
Where does it suggest Ahasuerus/Xerxes prevented construction? All it says is that complaints were made to him early in his reign.
I think you are creating more complications than there are. Understanding v. 6-23 as parenthetical, as relating to the later oppositions to city-building, is the most logical conclusion when all factors are considered - at least to me (and also most of modern scholarship).