You should disable depth clamping as it seems it interacts negatively with the way you use CSM.
Indeed, you are only adding the character in the shadow caster list: if you plan to only have shadows for the character, you would better use a standard shadow generator and have the light follow the character. It will be a lot less taxing on performances.
See for eg Best shadow parameters for specific scene - #2 by Evgeni_Popov and Best shadow parameters for specific scene - #12 by Evgeni_Popov for a method to tighten the light frustum as much as possible for a given mesh.