... the way I think that spelling would phonetically be pronounced in American English is with an "ah" sound rather than an "oh"
I'll disagree with you there. While I admit there are
many exceptions (three in a row in the beginning of this sentence!), generally when a vowel is followed by another vowel, either unseparated or separated by a single consonant, the first vowel is long.
Usually, the mechanism is 'silent E' ("Who can turn a
can into a
cane? Who can turn a
pan into a
pane? It's not too hard to see: it's Silent E." Thanks,
Tom.
), though it doesn't have to be a silent letter. Take
silent itself, or
begin or
pronounce or
duo, for example.
That being said, there are plenty of counterexamples, both of words with that pattern where the first vowel isn't long (like
there,
are and
many in my first sentence ... or is the 'a' in
many actually long, but elided? Hmm...) and vowels that are two (or more?) consonants away from the next vowel, and yet still long, like
horrible, or lacking a following vowel at all, like
go or
be.
In the specific case of
golem, I suspect that the cue to pronounce the 'o' as 'ah'
may have stemmed* more from the fact that it looks like a foreign word (because it is) and so we assume it has different pronunciation rules than English does.
*Further evidence: note the extra 'm' added to
stemmed, to keep it from becoming
stemed, which would be pronounced like
steamed.