I live in the US, and I've noticed that "challah" seems to be generally pronounced by Americans as something like /hala:/ (or possibly /ha:lə/), with either equal stress on both syllables or a slight stress on the first.
However, for some reason, I've generally assumed that the stress should be on the second syllable. Wikipedia seems to confirm this with [χa'la], and I seem to remember seeing similar pronunciation when watching an Israeli TV show.
Why is there such a discrepancy in stress? I wouldn't be surprised if American English speakers used something like /h/ in place of /χ/, but it's slightly strange that stress patterns have shifted. Is this just part of a normal shift in variation (similar to other treatments of foreign loanwords), or is there a deeper reason for this difference? (I would suspect so, but I lack the expertise to tell.)
Edit: Note: I am not exactly asking for something akin to "Why does American English have /dænts/ instead of /dɑːns/?" or "Why is there a discrepancy in the pronunciation of the English 'department'and the French 'département'?" One of the key things I'm interested is whether this might a result of variable pronunciation of חלה (and some Jewish groups being possibly more prominent in the US), similar to how there is variation in Hebrew pronunciations of religious terms (e.g. discrepancies between the Modern Hebrew, Israeli pronunciation and the traditional Ashkenazi ones, as far as I know).
Best Answer
Following up on aparente001's suggestion (in a comment above) to consult Leo Rosten, I offer this brief entry from his Hooray for Yiddish! (1982):
Rosten is evidently giving the Yiddish pronunciation; and as you can see, the first syllable is stressed in that pronunciation. Non-Yiddish English speakers undoubtedly patterned their pronunciation of the word on what they understood Yiddish speakers to be saying, as Peter Shor observes in a comment above. Where I live (the San Francisco Bay Area), some people pronounce the kh at the beginning of the word, but the more frequent pronunciation drops the k to leave HOL-leh (where the first syllable is indistinguishable from the usual West Coast pronunciation of hall). To my ear, at least, the first syllable generally receives more emphasis than the second.
In this area—which produces excellent breads of various kinds—challah is a common option at supermarkets/grocery stores as well as at bakeries, and I believe that the word is widely recognized and understood. One upscale grocery store near where I live sells three competing brands of challah. Unlike Rosten, sellers generally spell the word challah, with an h at the end.