I would say notifications of investigations are almost never given after the crime is committed, is vaccously true because literally nobody other than the ICC does the notice thing.

In almost every other system, investigations are kept secret. The complementary thing is pretty exclusive to the ICC.

I would also say that this is a matter of politics not justice, since such investigation notices are not addressed to the accused and in general it is expected that the accused is not told that they are the subject of an investigation. As such even if the notice was handled incorrectly, it wouldn't impinge on any of the accused rights and hence not be an issue of "justice"