Hi
You can see what COGNOS uses for mapping via this link:
Mapbox Global Boundaries Explorer v4
I have had the same issue with mapping and counties as it looks like COGNOS does not have them set as standard boundaries. If you look at the link above the country drop down when selected shows the District Council boundaries which are not the same as counties. Country Armagh is not the same boundary as Armagh, City, Banbridge and Craigavon - this is the council area not the county.
To get around this problem I have had to create my own maps using MapBox. I download a country geojson file from MapBox and then use it within COGNOS using the custom map links available on the map visual. I get the county geojson file from the OSNI website.
If you need more help with doing this then let me know.
Lorraine