The latest version the Curse launcher shows me is rhino-1.7.13-build.23 from 17.4.21 which is definitly not the latest version. And since KubeJS needs a later version I cannot start the modpack now. I guess it has to do with "Fabric update" yesterday to the Curse Launcher which now can shows you only supported mods for your launcher in the modpack. In my case this is forge.