Its a touchy and pedantic subject. 95% of people will understand what you mean when you say "Ireland", the last 5% will want to start a flame war over it because reasons.
https://www.nytimes.com/2018/10/18/opinion/england-ireland-b...
You do have to be specific about what you mean when you say "Ireland" in any context where it is important that you are understood.
"Ireland" can quite correctly either mean the island of Ireland or the country called Ireland (aka The Republic of Ireland). In a political or business context you are likely to be specifically referencing one or the other.
"Off Topic: Is the short form (Republic of Ireland) ROI used often?"
But also no. Cables landing in ROI would be under completely different regulatory control to cables landing in NI which would be under United Kingdom regulatory control.
In other words, based on your assumption that "Ireland" is precise enough and since Belfast (NI) has it's own IX, that would mean that you would have dichotomy where "Ireland" could connect to the internet and "Ireland" could not, yeah?
No doubt there are a great many other parallel situations out there. My dental hygienist took issue with the Netherlands being called Holland.