Retton had a mistake on FX in EF, and her vaults weren't great. Szabo's vault gold was questionable because her positions in the air were so wonky. IIRC, she did a piked Tsuk-full and a tucked Cuervo, but it was nearly impossible to distinguish one from the other. Mostepanova and Yurchenko went 1-2 on V in Olomuoc, so perhaps they would have done the same in LA.
Mostepanova also won floor in Olomuoc--tied with Gnauck, ugh! (This is supposed to be my Yurchenko fantasy. East Germans begone!) I don't know how things might have played out in LA. Szabo and McNamara were both amazing.
Sadly, I don't think Stoyanova would have been a major factor in LA. She was injured in early '84 and still wasn't at full strength for the Alternate Games.