Semantics aside, the planned assault on Parliament Hill was not considered as an Act of War (which would bring about the alternate terminology you suggest) but as a simple terrorist attack on the Canadian people. Do you mean to suggest that the FLQ did not commit acts of terrorism? That they were (are) a legitimate political force?

Still, current reports suggest that plan was abandoned and the current plan was to set off one or more bombs in downtown Toronto, a civilian target and a terrorist attack by any reasonable definition.