I believe Susan Rice gave a knowingly misinformed initial statement on what happened and if she really didn't know then she should not have said anything until more information was made clear to her, I believe when your a high profile public figure you should be careful about what you say.
Yes, Susan Rice should be regretful about Benghazi. Susan Rice purposefully lied to the American public about the situation in Benghazi. She immediately came out to the public and categorically stated that the attacks on the American embassy were the direct result of a Youtube video. However, this has been shown to be demonstrably false. Americans and family members of those who died in the attacks deserve the truth.
Hindsight is 20/20 and everyone regrets what they could have done in order to prevent a tragedy from happening. I don't think there is anyone involved with the situation that doesn't regret mistakes that were made. I think she also regrets how things were handled afterward as well with the media.
Yes, Susan Rice should have regrets for what happened in Benghazi, because Susan Rice was responsible for the horrible day. Those in Benghazi complained for more security several times. When the embassy was attacked, Susan Rice and Obama told reinforcements to stand down, and in doing so, allowed Americans to die. It was an abomination.
I think the tragedy in Benghazi was something that Susan Rice, as well as many people in the administration, should feel guilty about and have regrets about. It is a crime how many people in the administration will not face any type of responsibility for Benghazi. People died and there doesn't seem to be any type of justice.