If Ireland does not even want that cheque, it's not clear how EU should apply a different taxation retroactively. There's no chance in hell, no one, that this will stand.
If a european country in problem wants financial help from the rest of Europe, the EU asks it to collect its taxes first before they get the full help payed out. Happened in Greece when they asked for assistance, they had to collect taxes first, close loop holes and stop wasting money. Happened in Portugal. Will happen in Ireland as they also financial assistance a few years ago.
There is another point that makes me sure this will stand. The corporate taxes in Europe are all in line making it impossible for a state to lure big name companies away from other states. This is exactly what happened when Ireland tried to get all those companies relocate from Britain and Europe with those special tax deals.