I have the impression that CO usually does a pretty good job accomodating various languages. I agree that no scandinavian languages are needed for OSL/ARN/CPH, even small children speak English fluently in those countries. Same in the Netherlands.

In my view AF is the worst of all with languages. On flights to/from ZRH (which is German speaking) they just make the most important announcements in English (security briefing), all the rest just in French. They even refuse to speak English during the service in the C cabin! This is certainly one of the reasons why AF's market share out of ZRH is very low compared to any other major European airline.