How is it acceptable for us to call the Ohioan Russia: "Roo - shee"? Because we SAY so! Versailles? Why, let's call it "Ver - sails"....
We are Americans, so we reserve the right to butcher any foreign dialect that we choose. So, for the record, Qatar is not "Ka - tar' " according to the international consortium, it is actually "Cut' - ter". I say, who cares? Let's call it "Guitar," seeing as we know that's what it looks like. You mean to tell me the rest of the world doesn't put the accent on the wrong syllable for just about every English word they attempt to pronounce?
Linguistic historical progression (for those still reading and who have nothing better to do):
Ch'a (chah)
Chai (chai)
T'e (tay)
Tea (tea)
If you transport a word from one culture to another, something like this almost always happens in the process.