Similar? to the fallacy of the consequent...

The argument is formally valid, however, that does not mean that the argument is informally valid or that it has false premises.

Actor X chose to perform action Y, action Y created an undesirable (wrong) outcome Z, therefore the choice of Actor X is wrong

What does 'wrong' mean in this context? Morally wrong? Factually wrong? Personally disadvantageous?

....linked to If Actor X had chosen action A, the outcome would not have/ could not equal Z, therefore action A is true (the correct choice). 

Aside from more ambiguity regarding terms (in what sense do we mean 'correct'?), assuming A would have led to a better outcome, unsupported as it is, would be hypothesis contrary to fact 

Person X does action Y.
Action Y led to outcome Z. -> Do we know this? Suggesting this could be a fallacy in itself (confusing correlation with causation, causal reductionism 
Outcome Z was bad.

Person X did not do action A.
Action A could not result in outcome Z. -> Again, how can we be sure? This could be an unsupported claim or hypothesis contrary to fact 
Therefore, action A is correct.

If we know that action A could not have possibly resulted in outcome Z, and action A was a the alternative choice in a true dichotomy, then there is no fallacy. For example,

The $1,000,000 is in case A or B.
I chose case A. The $1,000,0000 was not in the case.
Sucks for me.
If I had chosen case B, I would not have chosen the case without the money.
Therefore, choosing case B would have been the correct choice.

Using the same example, if there are more than two cases, then we are dealing with a false dilemma .

If you like, comment with your specific example and I/we can provide further advice.