I think that your cousin should be old enough to face up to her responsabilities. If she had killed someone would she have skipped the country as well?
This is probably correct. With interpol and all that now and anti terrorism etc cooperation between police forces is at an all time high. If your friend skipped she would probably face imprisonment and not a ban
simple solution from her perspective - go to court and accept a driving ban, then head off & spend the driving ban period in another jurisdiction, where she either won't need a car or can possibly otherwise drive to her heart's content over there.
Or just lock her up for a while she might learn her a lesson. If she had have hit someone else in her drunk'n hase i don't think they would be able to forget about it as easy!!!!
a bench warrent would be issued which can be acted on the next time she set foot in the Irish jurisdiction - realisticly speaking I don't think they would pursue extradition given the fact that it is a "non fatal" case
A bench warrant is only issued when bail has been breached. An arrest warrant may however be issued or she may be convicted in her absence if she is summonsed to court. The OP does not say if she was charged with the offence after her arrest or released to be summonsed later. This makes a difference as if she leaves before the summons is issued then she may not be served with it. If she was charged and failed to appear in court it would have fairly serious implcations.
If she has an English one the Irish courts can impose a fine on her for drink driving but they cannot endorse, award penalty points or take a foreign licence away. I'm not even sure if they can ban her from driving in this country if she has a UK licence
As Ubiquitous said she should be talking to her solicitor