It may well be true that Ireland has the highest rate of false rape allegations. However, I would be very slow to accept this as proven because even if the study was carried out with scrupulous rigour, it is very difficult to collate reliable data for something like this. I think the most we can say is "it happens - perhaps more often than we would like to believe".
No justice system is perfect. I don't know what systemic failures ( if any) occurred in the Hannon case. But I think that far more witness interviews are now video recorded, which opens up the possibility of studying body language and other indicators that might show us a witness is lying. Likewise, forensic science continues to improve in leaps and bounds- I gather there was no physical contact at all between the accused and the accuser in the Hannon case, and the complete absence of DNA evidence today would surely sway a jury; But I don't know - this is just speculation.
I don't think we will ever have a justice system where we can say that there is no possibility of someone being unjustly convicted. But it is entirely possible that the particular circumstances which led to this conviction could not recur today. Or perhaps I am being unduly optimistic.