Quick question on Captain America and Green Lantern ID card inspiration effects

If say a character is inspired by this and uses energy explosion and hits 3 characters do I add 3 actions to my action total or just 1?

Looks like 3 to me. The hit is what triggers the effect. So each separate hit creates a separate trigger.

There are no other qualifiers to reel it in to once per attack or once per action.

yeah "whenever" is verbage that generally applies to each and every instance

if it were Boolean, it would usually have, well, "if" as the trigger check