(before you jump into discussion, remember that this only about these two individuals)
ICC and the prosecutor are on very solid ground here.
The prosecutor asked opinions from a impartial panel of experts in international law. The panel included people like Theodor Meron (former Legal adviser for the Israeli Ministry of Foreign Affairs), Helene Kennedy, Adrian Fulford.
Netanyahu and Yoav Gallant provided plenty of evidence of the intent. Did they really think that when they talk Hebrew to their audience, rest of the world does not hear them. Case like this would be harder to prosecute without evidence of intent.