I am kind of confused: EC Sonic Shriekers wording is "when a unit makes a Charge Move," but Charge Move is the last step of the charge procedure, and all reactions it is supposed to counter (Overwatch, Evade) are happening before that step. And this is the last step in the charging procedure.

However, in the general charge Sub-phase description, Charge Move is described as if it's an entire procedure of charge that starts with step one. In that case, Shriekers will counter reactions.

There are also contradictions about whether you may not choose to make a charge move (as for a unit), and simultaneously, in the Charge Move Step, it's said that you cannot choose not to make a charge move (as a movement after the volley step).