mistuning

“Wikipedia - Scordatura (literally Italian for "mistuning"), also called cross-tuning, is an alternative tuning used for the open strings of a string instrument.”

Netvouz - new bookmarks

“The talk radio word is that the classical music was lip synched, not played live, owing to concerns about cold mistuning the instruments quickly and wind noise.”

So maybe Chief Justice Roberts was instinctively editing and "improving" the wording of the constitutional oath.