I worked with a number of companies that received large volumes of cheques from customers/clients. One in particular had a long complicated name. There was a never ending number of variations of the company's name written on the payee line, (excluding parts of the name, including words that had nothing to do with the name etc.) I never recall a cheque being returned by the bank on the basis of these inaccuracies, so there appears to be a lot of latitude, whether or not that has a basis in law. In my experience the practice appears to be a lot more strict in the UK when're minor variations are regularly highlighted and cheques returned.
It could also be the case that the payee endorsed the cheque (depending on the crossing, if any) in which case it could quite legally have been lodged to a different account. Remember that cheques can generally be cashed by the bearer unless locked down with a strong crossing such as "A/C Payee Only, Not Transferable"
In any event, I'm not sure that you have a very strong case against AIB. The intended payee might have one, had it been lodged to an account other than his/hers, but I suspect you would have a lot of difficulty using this technicality to in some way try to prove AIB liable for the problem with your purchased item.