“Sometimes sea captains drift apart, I know it’s tough” Explaining to the kids that Dad and Cooler Dad are getting a divorce and there won’t be 2 Christmasses
Why does the main guy have a New Zealand accent? There were no Pirates from New Zealand. Let me guess, the makers were all Yanks? I've never heard of any Irish Pirates either, but Hollywood Pirate movies always have them. Meanwhile actors who have one of what must surely be over a hundred different accents that originate from England miss out on parts, because Yanks aren't familiar with them. The South West of England is where most real Pirates came from.
The creators are well aware of that. They weren't going for historical accuracy. It's a romantic comedy loosely based on reality. No need to overthink it.
You've never heard of any Irish pirates? May I respectfully suggest that your knowledge of piracy could stand to be enlarged? Grace O'Malley, the "Pirate Queen", was as Irish as her name suggests and was one of the most successful pirates in history. Ireland has been an absolute hotbed of piracy going back at least as far as 400 AD. St. Patrick himself was once abducted by Irish pirates.