Toi- let me just point out that medrash is part of torah. The Gra is not just legitimatizing the medrash.if you think nignaz means it can’t be found ( wherever you picked that up) than it means that without the gra quoting it. But if nignaz means it could be found (like I quoted before) than the gra does not suddenly disagree because it is in biur hagra.
