אמן in biblical hebrew can be amen, aman, or amén. Remember, the Masoretes preserved a tradition of vocalization, but the text itself only uses the we/vev as a vowel, and arguably the yod too.
Truly, verily, and most assuredly are the common translations I have seen for the biblical greek transliteration amen amen (as can be found in John 5:24). Fr. Laurent Cleenewerck, editor of The Holy Bible of the Eastern/Greek Orthodox Churches, based on the Septuagint and Patriarchal Text that I am so fond of, chooses to transliterate rather than translate this phrase. He renders it, amen and amen. You can reasonably expect a collaboration biblical audiobook, or two, from him and I in your near future.
aman beaman begins the ge’ez rite hymnography of the nativity (christmas), theophany (baptism), pascha (resurrection), ascension, and mt. tabor great holidays of the lord. For the sake of the melody, I translated this as truly, verily, and clips all over the internets, plus lived experiences of my students, have kept this combo alive for seven years.
Ge’ez and Hebrew have words that they share as distant Semitic cousins, but then there are Biblical Hebrew loan words to Ge’ez as well via millennia of Hebrew Bible reception. Shoutout to the Ethiopian Eunuch, his holiness Pope Athanasius, his beatitude Bishop Selama, and the nine greco-syrian saints. Aman is likely an organic Ge’ez cognate of the Hebrew, but a word like tsebaot (hosts, armies) is clearly a loan word when we already have the native seraweet, and many moons later picked up CHifra (CHibra) from the Oromo.
aman and amén are related to truth, belief, faith, agreement, and certainty. What are you least certain about? What are you most certain about?