All events are irreparable. Justice cannot be absolute, in either direction. This is not a flaw in morality, but in our limited abilities. Acceptance of that is not weakness, but awareness.
No amount of intelligence necessitates wisdom. Sorry Einstein.
Ya, somehow we think that releasing a falsely imprisoned person after decades is fixing it. We made it right! Well, no, you took away a significant chunk of their life, and likely ruined the rest of it as well.
That doesn't mean, however, that we should give up. We should be more careful about taking away life and freedom, and we should seek to make prison more fulfilling, so that people can have fuller lives when we deem them safe to be let out (because we discovered our error, or because they were rehabilitated).
The problem is complete irreparability. If someone is falsely imprisoned, you can't undo that, but you can free them, pay them some kind of reparations, publicly exonerate them, etc. If someone is found to be wrongfully convicted after death, what do you do? Essentially nothing.
Well, taken to its logical conclusion, this argument supports abolishing jail, prison and all forms of punishment, since the crime is irreparable, therefore there's no point.
But some events are more reparable than others. Releasing a falsely accused man from prison after 20 years doesn't give him those 20 years back, but it gives him back the rest of his life.
And suggesting that because all events are irreparable, all events are thus morally equivalent is morally reprehensible.
No amount of intelligence necessitates wisdom. Sorry Einstein.