Interesting -- apparently the non-self-executing ICC jurisdiction inside the Magyar state is being held up on a question of head-of-state immunity. International law consists of many sensibilities overlaid, not just in space, but also in time. And there are some jus cogens rules that antedate any legislative enactments. Of course, in the present case, this presents a difficult political question.
https://szakcikkadatbazis.hu/doc/8612513