He's the hardest boss of the game in that version. I get that it isn't in the spirit of the game but Borgan should have died. Miria Ausa is an entirely too forgiving dumbass.
I think Zophar is harder overall, mainly because you can reduce Borgan's damage output with the right gear (Gravity Bomb is fire-elemental, which I didn't know the first time through the game), but even with Pressure Cooker, Zophar 2 hits hard.
And to follow up with what you said, the same should also apply to Lunn, but I get more where Jean's logic and character, as an individual, is coming from, versus the freaking head of a city-state.
Lunn is probably THE ONLY character in the Lunar games that I don't like. Bad voice acting and just generally bad everything. Nash is a douche but at least is good as a character.