A certain amount of that would happen yes, but Ireland does significant work around the world to induce demand for our agricultural outputs like milk/beef/pork. There's a fairly strong argument that there are people in other countries swapping from more vegetable/local based diets to high CO2 output diets including milk/beef/pork from countries like Ireland.The fact is that if we cut back our agricultural output because of CO2 levies somebody else is still going to have to produce that food because brits and Germans still need to eat.
However I agree with you that if the agri emissions that would simply shift to other EU countries can be identified, it is unfair that Ireland should have these added to our total.