At a minimum the language used for safety briefings should be language of the departure airport, the language of arrival airport and English.
If audio/video presentations are being made the cabin crew should ensure that the cabin is prepared for the briefing. i.e. all passengers seated and advised to pay attention.
The largest airline in Geneva, on UK registered aircraft, play a tape in french while passengers are still on their feet and attending to their hand luggage etc. Then they give a demonstration in English (often spoken much too quickly, and in broad accents) On their Swiss registered aircraft they give the demonstration in French, German and English.
Other announcements are less critical, particularly those trying to sell you 'scratch-cards'.