I further examined the book Yuchasin and understood that his intention was not regarding the mentioned time, but only about the compilations of the Mishnah, Sifra, and Sifrei, which were completed six hundred years after the passing of Rabbi Akiva. And that is the truth, so there is no need for correction.
Nevertheless, it is as if Rabbi Shimon bar Yochai himself authored them, since these concepts originated from him initially and then were transmitted and passed down to later generations. It is fitting to be attributed to him (and similarly, many of our ancient books are named after individuals who were remotely connected to them, as evident from various sources).