That warning is telling you that because of the length or content of the level's display level (which could include HTML, etc.), when you are working in creating utility reports or simulations that having such long text may make the reports look bad and hard to work with.
Especially if you intend to provide a simulator to clients, a long blob of text or HTML would look fairly bad.
To alleviate this, where you define the attribute display text there is a field where you can type in a shorter, more to the point internal label that will be used by the software in these places.