Many of the posts here have brought out very valid points.
Essentially, there is no need for two consonants or vowels if the two sound identical. Hence, letters like sav, samach, sin, must have sounded different from each other at one time. So too with kaf and kuf, het and chaf and the like. Some groups, all of North African or Oriental origin (syrian, egyptian, yemenite)distinguish between these sounds, although these differences are inaudible to the untrained Anglo-Saxon ear. What we are left with is what we were taught as children, and that should be good enough. A little tolerance goes a long way.
As far as accenting the proper syllable, it seems that at least several hundred years ago, the Hebrew language as davened with or as learned with among ashkenazim, moved into a “mil-el” pronunciation. SHAbbos, TOrah, LUlav, SHOfar are all accented mil-el, but proper grammar would demand mil-ra, as in shaBBOS, luLAV, etc… Consequently, it is extremely common to hear all types of ashkenazic Jews, misnagdish and certainly chassidish, accenting mil’el as opposed to mil-ra when they daven. Is it grammatically “correct”?
I say, no, it is not, but so what? They know what they mean, God certainly knows what they mean, their intentions are pure, that’s the way they were taught by erliche yidden, so lay off, it is perfectly fine. My only exception would be when the misplaced accent changes the meaning of the word, a famous example coming up in Parshas Balak, “Ki lo NAchash be’yaakov” needs to be read mil-el, as NAchash means “magical incantations”, which is pshat in the posuk. To read it naCHASH would mean “snake”, which is clearly mistaken .