If you’re talking about the International Criminal Court established by the Rome Statute you’re absolutely right, every single person indicted or wanted by the ICC has been an African and, other than Libya, all of them concern situations in Sub-Saharan Africa.

To be clear I absolutely support bringing to justice perpetrators of these heinous crimes. At the same time I question the fact that an institution created by Europeans purports to bring justice to Africa when European colonial practices used systematic brutality to rule Africa, the same kinds of atrocities such as mass murder and mutilation that these defendants are accused of. I question the fact that Europeans were able to destroy and weaken indigenous systems of governance in Africa, which led to the chaos and conflicts in the first place, and then rush in to fill the institutional void. I question the fact that Europeans and descendants of Europeans still use violence with impunity in Africa, Latin America and other resource-rich “poor” regions of the world and you never see and I predict will never see a white face in the docket of the ICC, at least not for killing people of color. (There is one European situation under investigation, in the context of the civil war in Georgia.)

Now if you expand the question to other international tribunals the answer gains a few wrinkles, since the main precursors to the ICC are the Nuremberg Tribunals after the end of World War 2, the International Criminal Tribunal for the formal Yugoslavia (ICTY), and the United Nations Tribunal for Rwanda (ICTR). All of these were ad hoc tribunals set up to address specific conflicts and meant to close shop when their mandates were done, as opposed to the ICC which is a permanent tribunal whose jurisdiction covers potentially any conflict happening anywhere (in practice exclusively in Africa so far, as discussed above). The Nuremberg Tribunals and ICTY did in fact indict and convict white people, but for crimes committed against other Europeans. It should be noted, though, that the bulk of the genocides were committed against groups whose claim to whiteness is contested and complex, such as European Jews, Romani, and Bosnian Muslims. 

In addition to international tribunals there are also domestic courts, which also have jurisdiction over war crimes and which actually try the bulk of war crimes due to problems of jurisdiction and sheer volume. The United States, for instance, has not ratified the Rome Statute so the ICC has no jurisdiction under normal circumstances over war crimes committed by U.S. personnel. In fact the United States has said it is willing to use force to rescue any citizen arrested by the ICC. Also international tribunals such as ICTY, ICTR, and the ICC try high-profile defendants such as heads of state and generals. If they tried to convict every defendant they’d quickly be overwhelmed, which leaves the small fry to the domestic courts. And countries like the United States do prosecute and convict their personnel for war crimes, although it’s not nearly enough in my opinion and too many get off without consequence.

On some occasions nations try foreign nationals for crimes against its people, what might be called victor’s justice, as in the case of Israel trying Eichmann. In Israel’s case the “victory” was that the Jewish people were not entirely destroyed, not to mention victory against the British Mandate and the Palestinian people in setting up their own state, rather than military victory against Nazi Germany. Victor’s justice is usually discussed in a pejorative context as not being justice at all, such as the way many Allied personnel faced no charges for war crimes committed during and after World War 2. In Eichmann’s case I think it actually worked, though, both morally and legally, since his trial wasn’t some kangaroo court but rather was fairly conducted.

The above is a long setup to say: with regard to Kylo Ren or someone like him, history tells us that the best hope for justice is actually victor’s justice. His situation is unlikely to go to an international tribunal because there will likely be only one state left after the end of the conflict, either a successor to the New Republic or whatever state or state-like entity is set up by the First Order. This means Kylo Ren would be tried by a domestic court rather than an international tribunal. If the First Order wins he’s not going to face any kind of justice for his crimes, except possibly for insubordination or treason if Hoax wins the internal struggle. If the Resistance wins Kylo Ren will face charges and most likely be convicted with the sentence being capital punishment or life in prison, unless the bench is entirely staffed by Reylos and Kylostans of course.