Yes, you are correct. When you import a MediaShout 6 song library, it does strip away the backgrounds and things. We hope to one day improve this to allow those to carry over, but I'm not sure when that would be implemented. I apologize.
In the meantime, you may be able to import your MediaShout 6 scripts that have the lyrics in them with the background and everything. Then, you can save that to the Cues Library for next time.
Let me know if you have any other questions.