Then copied the Global files of Cyseal (Data\Mods\Main\Globals\Cyseal\Characters) to my mod module and loaded my module: saving changes on characters seems to work, the scripts are added. Closing the editor, starting and loading my module: changes are gone. Adding scripts again: can't be saved due to missing developer rights.
Instead of copying the files yourself, have you tried just:
Right click >Copy selected objects to mod?
I haven't tried using custom made scripts but I have been able to change scripts. For example I changed the tutorial skeleton from having a mustard gas grenade to having an ice grenade.
