Harry wasn’t super familiar with mind healing, but the book he had in his office about legilimency and the mind did talk about how the spell could be used to help those with memory issues. The legilimens could go into the other’s mind and search for the missing memories. Oftentimes they were hidden behind a wall. In ways, it was similar to what a magical did with occulmency, but in this case it was a wall the memory owner couldn’t move past. His goal was to help Gibbs move past that wall.