I speak some French and German and I've never seen anybody collude in a non-English language. Whenever this happens, I just write "Man muss nur Englisch am Tisch sprechen!" or "On doit parler seulement Anglais à la table" and they usually apologise and quickly switch back to English.

Besides, PS have staff who speak a whole bunch of different languages (particularly European languages) since they have customer service centres in various European locations.