Assuming all the ancient Jedi texts were destroyed in The Last Jedi, are these Luke's personal notes? And did she return to get them or were they in Leia's possession?
Rey took them from Ahch-To in The Last Jedi, we see them aboard the Falcon at the end of the film.
This is confirmed in The Rise of Skywalker: The Visual Dictionary:
It was Luke Skywalker's conviction that the library on Ahch-To should be destroyed, as the Jedi Order had been locked in a ruinous cycle of galactic upheaval since its very inception. Rey - perhaps driven by her innate scavenger instincts - left with the books before they could be burned, hiding them aboard the Millennium Falcon without he Master's knowledge.