For cultures, I would make New-Brunswick, Nova Scotia and Prince Edward Island as one single culture. You could call it Maritimes, it is how it is refered here in Canada.
When playing with provinces on, the Northern part of Maine is called USA which seems off. Same for Puerto Rico being just USA.
At some point it would be fair to make less provinces for smaller islands or more provinces for some continental places. For example, Nunavut has 67 provinces and Greeland 19 despiste being similar sizes. It makes Nunavut more vulnerbale to events related to coastlines and less vulnerbale to be completely erased from the map. The same could be said when you compare Panama with 15 provinces and Québec culture with only 5 or comparing Brasil with 32 and Chile with 49.
I am curious by how you dicided to divide the world and countries into provinces? Do you aim to make every province with a similar size, a similar population or a similar development?