Web/Light Novel Spoilers
Actually the novels don't really focus much on punishing the heads of nations that Japan conquers. IIRC Remille actually manages to escape and fly under the radar for a long time; I don't even remember if they actually do capture her or not, though I want to say if they do, she's basically held prisoner in Tokyo crying at how stupid she was to underestimate Japanese superiority. I could be confusing her with another female superior from an enemy nation, it's hard to remember, and they barely devote any time to talking about these things.
Edit:
I went back and reread and they covered it more than I remembered, but it was still only half a chapter, and it's basically as I said - Remille is taken prisoner, cries over her insolence in prison, and then we never hear from her aga