A conservator is not financially responsible for poor judgment in handling financial matters. The conservator would only be held personally responsible if it were shown to a judge that the conservator was stealing or otherwise committing fraud, or had recklessly risked the person's assets.
If you or other family members think the conservator is consistently making bad decisions for your family member -- either financially or in terms of her personal care -- you can file court papers that raise these issues and have a judge decide whether the conservator should be replaced.