Is it acceptable to say "America was discovered in 1492 by Columbus" or is it only acceptable "America was discovered by Columbus in 1492"?
Either order is fine from a grammatical standpoint. The first emphasizes that it was Columbus, the second emphasizes the year.
(Thought it's commonly said that Columbus "discovered" America, there were, of course, people living there when he landed.)
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.