You can't just walk across a recognized international border and do the "right" thing without a consent, regardless of how right or wrong it had been. That's an act of war, technically.
There's just a distinction to be made from intentionally killing civilians for the purpose of causing terror versus targeting a group that you are in an open military hostility with. The second one, as you say, is basically just war. And war has historically also included civilian casualties.
Flying a plane full of civilians into a building full of civilians, or detonating a bomb in a public square full of civilians, are pretty clear examples of what "terrorism" is. They aren't actions meant to directly attack the capability of an enemy to wage war against you.
What governments and media choose to label "terrorism" or "terrorist groups" however is inherently political and not done following some agreed, objective definition.
They’ve been at war for 50 years, like, officially the war declaration was never dropped.
So recent missile volleys can’t be treated in isolation, despite that making sense
How would you call that?
There is already a war, so far it just has been avoided to become an all out war.
You might want to read up on the killing of bin Laden, Entebbe raid, and many other similar operations.
It’s part of the deal when you’re a high speed, low drag type. Be good, or get dead.
They could decide to build up their country and Israel wouldn't interfere.
If a platoon of American CIA agents went around the US executing 'bad people' (definition problems notwithstanding),
That would be bad.