What is the standard of review for a jury trial on a charge of reckless driving enhancement?

The People agree that defendant's right to a jury trial on the enhancement was violated but disagree that he was prejudiced, under the standard of review in Chapman v. California (1967) 386 U.S. 18. (See, e.g., People v. Bautista, supra, 125 Cal.App.4th at p. 656.) The People point out that the jury found defendant "proximately caused great bodily injury" to Granados. (Veh. Code, 23558.) "Proximately causing great bodily injury" is, the People argue, the same as "personally inflicting great bodily injury," and therefore the error was not prejudicial.