Is a prosecutor's use of immunity agreements while examining five witnesses harmless beyond a reasonable doubt?

In light of the prosecutor's use of the immunity agreements while examining the five witnesses, which was proper, the admission of the immunity agreements themselves was merely cumulative and, therefore, harmless. (See People v. Schmaus (2003) 109 Cal.App.4th 846, 860 [confrontation clause error harmless beyond a reasonable doubt if " 'the properly admitted evidence is overwhelming and the incriminating extrajudicial statement is merely cumulative of other direct evidence'"]; U.S. v. Nielsen (9th Cir. 2004) 371 F.3d 574, 582 [confrontation clause error harmless beyond a reasonable doubt where extrajudicial statement was of "minor importance" and there was "cumulative evidence of [defendant's] guilt"].)