Add attribute to SCR_VoiceoverSequence and SCR_VoiceoverLine that allows to define signal values when sound event is played.
Then in SCR_VoiceoverSystem.PlayLineActual you'll have something like
signalManager = SignalManagerComponent.Cast(actor.FindComponent(SignalManagerComponent));
foreach (s : signals) {
signalManager.SetSignalValue(signalManager.FindSignal(s.m_sSignalName), s.m_iValue);
}