That’s because there is more involved than simply moving files around. The game flags Custom mode (mod) characters when they are created. Main Campaign character’s do not have this flag and thus you need to use a character editor to set this flag if you move them to custom game save directories. GD Stash can help you set this flag.
If you’ve never used GD Stash before be aware that on first run of the program you will want to verify that it has detected the correct directories it needs and then you will need to ‘Import database’. This will take several minutes but it must be done before you can proceed.
As for your other “complaints”, all of GD’s mod tools are located in its root installation folder along with a general (but detailed) PDF guide on how to use them.
