Adam Clarke on Ezra 4:7

In the days of Artaxerxes - After the death of Cambyses, one of the Magi named Oropaestus by Trogus Pompeius, Smerdis by Herodotus, Mardus by Aeschylus, and Sphendatates by Ctesias, usurped the empire, feigning himself to be Smerdis, the brother of Cambyses, who had been put to death. This is the person named Artaxerxes in the text: or, following the Hebrew, Artachshasta. It is generally believed, that from the time of Cyrus the great, Xerxes and Artaxerxes were names assumed by the Persian sovereigns, whatever their names had been before.

Written in the Syrian tongue - That is, the Syrian or Chaldean character was used; not the Hebrew.

Interpreted, in the Syrian tongue - That is, the language, as well as the character, was the Syriac or Chaldaic.