That is dreadful - my understanding is that a UK EPA may not be valid in Ireland and that to be sure, there should be an EPA in any jurisdiction where assets are held.
I suspect that you might be able to access cash assets here with the UK EPA but I don't think you could sell property.
You may have to go the road of Ward of Court - it is a bit drastic but sometimes can be the only answer to make sure that people are adequately looked after.
If your "reality challenged relative" - (I love that description - it describes my own dear mother rather well) would not be distressed ( as in would not grasp what was happening and oppose the application) it can be done relatively quickly and painlessly. I find the Wards of Court Office in Smithfield excellent to deal with, albeit given the antiquated laws they work with.
mf