My opinion is that you should be forgiving of the person's actions pre-diagnosis. Usually because of the effects of the mania, they don't even realize anything is wrong. It's like being high without choosing to take any drugs (not talking about drug abuse that sometimes happens during mania), it is an altered state of consciousness in which judgment is impaired, reality is distorted, and usually people regret a lot of their actions afterward.

However, once a diagnosis is given and treatment begins, and the person has the ability to recognize an episode in themself, and they either deviate from treatment (like skipping meds) or don't try to get help or inform others, I think you can start to hold them accountable for their actions.

This is just my opinion as a bipolar person...