IIRC, there were former intelligence official that night on TV saying they'd heard through channels that it was clearly a terrorist attack.
We now know that to be true. We also now that the Bengazi embassy was on the phone to US officials describing the attack as it happened.
I.e., the US knew immediately that it was a terrorist attack.
If I can get that info from former intel officials on TV that night, I'm going to bet Romney had even better info.
So, yeah, it looks like he knew exactly what he was talking about.
Fern
The problem with Romney's response wasn't his characterization of the attack (you could certainly argue that attacking a consulate with heavy weapons is a terrorist attack no matter what). It's that he INSTANTLY jumped all over Obama in an embarrassingly partisan display without having any information at all to base his attacks on other than "Obama is President", "The consulate was attacked", "Obama is my political opponent".
And the debate has never, as far as I know, been about the nature of the attack so much as the cause of the attack and the environment surrounding it. In other words, it was clearly a terrorist action (I think Obama even said so the very next day), the question was whether it was motivated by the video and/or stemming from protests in other places or local protests.
Bottom line, the problem wasn't Romney calling it a terrorist attack (which seems reasonable), the problem was attacking Obama before he had a reason to do so outside of blatantly obvious political ones.