Thank you for helping me find a term for that, I may also go with English/Scottish/Irish names, or at least ones that sound appropriate for the positions, as the nation in the setting is strongly allied, and influenced by(the people who populated the island originally came from the mainland nation), another country in the setting that is based off of England, Scotland, and Ireland.
How does; grand general, minister of finances, and.....high diplomat?, sound?
I may avoid tension between the three for now though, as at least currently, the only one that might try to remove the others is the diplomat(and the triumvirate in this case is elected, for 50 year spans or until a member dies or gives up the position.