Even speaking as a US citizen, I can admit that the actions of some rebels did constitute terrorism. Innocent Loyalist civilians were targeted, for the purpose of political change. It doesn't get much closer to the textbook definition of terrorism than that.
The actions of many national armies in wartime counts as terrorism by application of various textbook definitions was well. That does not make those armies or their soldiers terrorists.
I disagree. However, nobody wants to admit that their team did evil things, so we whitewash. Very rarely do people see anything but black and white when it comes to 'Us vs Them' situations.
Then you are extending the definitions of "terrorist" and "terrorism" to such broad lengths as to make the terms useless for anything except political and propaganda purposes. It has nothing to do with admitting to or denying evil things.
Terrorism is political violence, but not all political violence is terrorism. Terrorists use political violence to further their ends, but not everyone who uses political violence is a terrorist.
But hey, the winners write the history books.