Correct.
> What if the scale changes from 14,00 to someone taking down key pieces of the power grid
Still not terrorism.
> I’d want the authority in charge to absolutely treat this or any attack on infrastructure as terrorism.
Sure, but only until they determine what it really is.
Terrorism is hard to define exactly, but some required elements are that it be an attack on civilians (an attack on military or police is never terrorism). And it must have a goal of some kind, they must want to change something, by making people scared of another attack.
If you attack people because you hate them, that's not terrorism unless your goal is to change some law or reality (for example make them scared to leave their homes). If you just attack out of hatred it's bad, but it's not terrorism.
If i was homer simpson and caused a nuclear incident due to negligence, it's still not terrorism.
[0] https://www.fbi.gov/file-repository/fbi-dhs-domestic-terrori...