I use libretro with various cores. I some, like PSX, you need the “bob deinterlace” in software mode. In some others, i like the Crt-easy mode shaders. Well, for me, the shaders presets are loaded correctly, but not are applied to the core (i must go to the “shader” menu and hit “apply changes” to get it work).
If i am doing something wrong, please tell me.