Brian, et.al.

“investigated, widely condemned publicly, and the perpetrators and their superiors prosecuted.”

I think you misunderstand the process.

Unfortunately, the UN has no authority to punish soldiers leant to it by members states (actually thank america for leading the pack in pressing for this). All the UN can do is investigate claims- which has been done- then send home guilty soldiers to their respective countries and strongly urge the governments to prosecute their soldiers (which they are relectant to do).

You seem to want it both ways- on the one hand americans dont want to let the UN prosecute american solders or citizens on the other hand you complain when the UN does not prosecute soldiers or citizens from member states.

So which is it that you want? To give UN authority to punish soldiers from members states ot not?