The fact that there exists a, and only one, power in the constitution to bring about war, that is, armed conflict with another nation, means it must be used for an armed conflict to be authorized.
If the Congress authorized the executive to "take action" then the enacting clause damn well will be 1-8-11. Otherwise that "authorization" is illegal, and void, because that is the only place in the constitution that authorizes any branch to take the nation to war. If Congress made that authorizaton under 1-8-11 then it doesn't matter if they call it a "declaration of war" or not, it is one.
So, did that "authorization to take action" use the powers of 1-8-11? If it didn't then it is a violation of the separation of powers. I don't think it did, because there is too much scrutiny and too much complaining about no declaration among those who investigate these things closely.
Frankly, Congress pulling a extraconstitutional power out of it ass frightens me, and it should frighten you, too.