EU4's Content Design Coordinator, the wonderful @Pavía, holds a PhD in medieval history - so you are correct that it's an important skillset in developing the game.
To answer your question about working for Paradox, I would recommend you sign up to be notified of future opportunities on the Paradox careers portal. If you're interested in working for Paradox Tinto, relocating to Spain may also be in your future.![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
To answer your question about working for Paradox, I would recommend you sign up to be notified of future opportunities on the Paradox careers portal. If you're interested in working for Paradox Tinto, relocating to Spain may also be in your future.