Hello and welcome to the forum! Glad you joined us.
Feather barbering is a feather destructive behavior, they pinch the feather off, sometimes down to the skin, when plucking, they pull the feather out. When a bird pulls out a feather, endorphins are released, when that happens it causes a temporary sense of calm, some birds get addicted to the endorphin rush. If your Goffin has stopped plucking and is still barbering, as strange as it sounds, that's a big improvement. The barbered feather shafts will molt out and be replaced with new feathers. There's no way to predict how long the barbering will last. Has your bird been treated for plucking, if not, a thorough examination by an Av Vet and bloodwork may be in order. Good luck to you, please keep us updated.