Hello! If I understand your use case correctly, you are randomly picking a random Input setup class and you want to get the computed level description. As this is not a mainstream use case, I would propose the following solution. Instead of using the DungeonGeneratorInputBaseGrid2D class directly, make a child class instead, something like MyCustomInputBaseGrid2D and on this class, you can add a custom public MyGetLevelDescription() method that calls the protected method. Then, in your RiftGeneratorInputSetup, instead of referencing DungeonGeneratorInputBaseGrid2D, you would reference MyCustomInputBaseGrid2D so that you could call MyGetLevelDescription() directly.
Let me know if it helps.