I don't think the "only" means "The system only" but "only if". Because it explains the case when the system doesn't call the methods as well. (...)The system doesn’t call this method if the synthesizer is in a delay between utterances when speech stops, and it doesn’t call it for unspoken utterances.

Same. I use Xcode 16.3 + iOS 18.0. I am considering downgrade Xcode..