“Why do most people pronounce the first two words of the Kaddish as ??????????? ????????????? when the ??”? demonstrated that those two specific words are not Judeo-Aramaic but ???? ???? and should thus be pronounced ??????????? ?????????????? (See ?’ ???? ??.)
Why do most people say ??????????? when, as the ??”? demonstrates, the ?”? should have a ???? (The word should be ????????????. Again, see ?’ ???? ??.)”
Because there are those who are choleik on the gr”a. (I think the yaaveitz, but am not sure.)
Interestingly, the mishna berura writes like the gr”a regarding your 1st paragraph, but not the 2nd.