Thanks.
It didn't seem likely, but I was thinking earlier today that with one of the common Hebrew pronunciations*, "omen" actually makes more sense as a spelling than "amen" does. And the train of thought proceeded from there.
*In English, it's "AY-men", but that's not how it's said in Hebrew at all. The way I would say it is "ah-MEHN", but it's also common to say "oh-MEYN".
The English pronunciation (the first vowel, anyway) is a result of the Great Vowel Shift. Of course, some English speakers still say "AH-men", apparently from the traditional pronunciation when sung, which is much closer to the original.
I don't know much about Hebrew dialects, especially historically, but I would guess that it was either
amen historically, with some dialects moving to the
omen pronunciation sometime after it was borrowed into Latin, or both forms existed historically, but the word was borrowed from a dialect that used the
ah pronunciation.