Download tar signed with unknown key and incorrectly in "stable" directory
The 0.5 download tar for kaidan is signed with an unknown gpg key melvo@olomono.de AE08C590A7D112C1979D068B04EFAD0F7A4D9724# but there is no mention of this on the release announce blog or any indication of where to get this key.
The tar is in https://download.kde.org/stable/ but it is not stable and should be in the unstable directory.
The app will need to go through kdereview process before it can get a stable release https://community.kde.org/Policies/Application_Lifecycle#kdereview