Aren't England, Scotland, and the Irish Republic as complicit as Northern Ireland and Wales? They were all run by the same government.
The government was the government of England which ruled over Wales and Ireland. Scotland was a separate country until the Act of Union in 1707. Individual Scots and Welshmen and maybe Irishmen may have been involved, but the Irish Catholics weren't much better off than slaves themselves--in fact I think some were enslaved and sent to the Caribbean for resisting English rule.
"Aren't England, Scotland, and the Irish Republic as complicit as Northern Ireland and Wales? They were all run by the same government."
England and Scotland, sure, but the Irish Republic? It didn't exist then, and the government that did exist over what is now the Irish Republic was a government imposed from without that the Irish didn't want. So, no, the Irish Republic is in no sense whatever guilty of the slave trade, and nor are the Irish Catholic people, who were victims of the same Empire that victimized the African slaves during the same period. Not guilty.