Were amazed (existanto). Imperfect middle of existēmi, to stand out of themselves, wide-open astonishment.
Marvelled (ethaumazon). Imperfect active. The wonder grew and grew.
Galileans (Galilaioi). There were few followers of Jesus as yet from Jerusalem. The Galileans spoke a rude Aramaic (Mar 14:70) and probably crude Greek vernacular also. They were not strong on language and yet these are the very people who now show such remarkable linguistic powers. These people who have come together are all Jews and therefore know Aramaic and the vernacular Koiné, but there were various local tongues “wherein we were born” (en hēi egennēthēmen). An example is the Lycaonian (Act 14:11). These Galilean Christians are now heard speaking these various local tongues. The lists in Act 2:9-11 are not linguistic, but geographical and merely illustrate how widespread the Dispersion (Diaspora) of the Jews was as represented on this occasion. Jews were everywhere, these “Jews among the nations” (Act 21:21). Page notes four main divisions here: (I) The Eastern or Babylonian, like the Parthians, Medes, Elamites, Mesopotamians. (2) The Syrian like Judea, Cappadocia, Pontus, Asia, Phrygia, Pamphylia. (3) The Egyptian like Egypt, Libya, Cyrene. (4) The Roman.
Jews and proselytes (prosēlutoi). These last from proserchomai, to come to, to join, Gentile converts to Judaism (circumcision, baptism, sacrifice). This proselyte baptism was immersion as is shown by I. Abrahams (Studies in Pharisaism and the Gospels, p. 38). Many remained uncircumcised and were called proselytes of the gate.