That's an interesting comment that your sister made and I am glad that she is personally aware of this because whether she chooses to stay or leave if she can identify these problems then she is not devoted to the GB and is unlikely to follow their lead in all things.
The March 2012 study Watchtower is making an attempt to deal with internal wrongdoing. They tend to explain it away as just misunderstandings. This is from the study article titled "For those loving Jehovah there is no stumblying block
...For example,he recognizes that what seems to be an injustice to us may be a misinterpretation or a misunderstanding on our part. Jesus will handle congregation needs perfectly and at the right time. Thus, we should not allow the actions or decisions of any fellow Christian to become stumbling blocks to us.."
The logic in the article is so typically bad.
The organization just tries to push things under the carpet and pretend that injustices are not real but even though they are not real Jesus will deal with the problems at some unspecified time and in some unspecified way. Which simply means that the org. has no intention of dealing with these problems themselves.