Can I change usernames while using Guest Author?

https://www.wpbeginner.com/wp-tutorials/how-to-change-your-wordpress-username/
I’d like to use either method 1 or method 2 of this guide to change the username of one of my users, but it’s an important website and I have to be sure that renaming won’t cause any issues with Guest Author. Many posts of this user have been attributed to a guest author.