The Lugano Covention means that EU court orders are almost always immediately valid across all EU and EEA member states, and while that leaves out countries like the UK and Serbia, their courts will usually confirm court orders from other European countries (and it would be a big diplomatic incident if they didn’t in this case). Equally important, Ireland is a signatory of the Lugano Convention through the EU, so Ryanair would have more to lose than planes really fast if they decided to be irrational.