"You misunderstood": does it actually mean anything?
I first heard it from an SCJ teacher, who had previously told me that I could make up an excuse to my parents if they seemed concerned about me spending long hours at Bible study. She told me I could say I had "spent some extra time in the [university] library". Immediately, I recognised that as a lie, but didn't bring it up to her until later on.
When I finally texted her to ask about it, I said that lying to my parents just seemed wrong. Her response was, "I think there is a misunderstanding".
She went on to explain that the reason she encouraged me to use excuses with my parents was because she didn't want them to persecute me for going to Bible study, just as her parents had previously done to her. I replied that a lie was a lie, and I absolutely couldn't see how I could have misunderstood her.
I also repeated to her that it was wrong to lie, even if it was to stop people from persecuting you, and her response was "I'm sorry for the misunderstanding".
I definitely think it's possible to legitimately misinterpret SCJ's doctrine, for example, I've seen some news articles that describe Lee Man-Hee as the Second Coming of Jesus Christ. From what I've read from ex-member testimonies as well as pro-SCJ websites, I think that's a bit of a misrepresentation (however, this does not make SCJ's doctrine correct). So yes, it's possible that "you misunderstood" could really mean "you misunderstood" when applied to these kinds of situations, but otherwise, it just seems like a phrase that SCJ members like to throw around to make you think you're doing something wrong.