They might be overjoyed. Since Sarada is part of their family, they would likely welcome her with open arms and big smiles. They could be very proud of how far she has come in her ninja training.
One possible scenario in the 'Sarada Meets Her Grandparents Fanfiction' is that Sarada is initially a bit nervous. But as she starts talking to her grandparents, she realizes how much they care about her. They might take her on a tour of their old home, showing her all the places that are important to the Uchiha family. This could help Sarada feel more connected to her roots and give her a stronger sense of identity within the clan.
Perhaps Sarada would try to interact with them, but she has to be careful not to change the past. She could watch them train together and understand the origin of their teamwork. This experience would give her a deeper connection to her family's history.
One possible scenario in this fanfiction could be Fugaku seeing Sarada's potential and taking her under his wing to train her. He might recognize her Uchiha blood and want to ensure she becomes a strong shinobi like the Uchiha of old.
In this fanfiction, his grandparents might be described as having a deep connection to the magical land they live in. They could be the keepers of ancient family secrets. Their physical features might be aged but still show signs of the great beauty and strength they had in their youth. And they may be very loving towards Harry, making up for the lost time they could have had with him.
This encounter in the past fanfiction could be a turning point for Sarada. She might start to see her place in the family in a new light. Maybe she'll become more protective of her family's legacy, and it could also change how she approaches her own ninja training, as she now has a newfound respect for her parents' skills and experiences.
In a Sarada meets past Sasuke fanfiction, it could be that Sarada has to keep her identity a secret at first. She might be on a mission in the past for some reason. As she observes past Sasuke, she could notice his skills and the way he interacts with others, like Naruto. This would give her a chance to understand the bond between her father and Naruto from a whole new perspective, which could be really interesting for the readers.