were the contras 100% backed up by the U.S? Could we ever forget what the U.S has done to us and suck their tit like Costa Rica has done? Nicaragua was clearly a huge piece for however controlled it on the Cold War era, just as some say that the CIA goes into countries and put right wing governments, Soviets or Cubans did the same back in the '70s to Nicaragua?
What do you mean by "meant to fail?" Do you mean the FSLN's intent to govern? The FSLN was quite serious and governed for over 10 years. Or do you mean could their movement last long term? You'll probably get a better answer about the extent of US intervention, but considering that the US funded and trained the armed opposition I think you could classify its level of interference as quite high.