I have never messed up my name in flight ticket (except that I never state my middle name which is clearly stated in my passport but that has never turned out to be a problem at > 100 flights) so NO, I have no personal experience, but it has been reported so many times in various FF threads that minor name mistakes are not going to be a problem. Switching names is considered to a very small and common mistake.

Anyway, if you will worry about this until departure, I suggest to go ahead and ask Exp to make the change to get it over with. Cathay Pacific has correctly referred you to deal with Exp - they cannot/will not touch your ticket until the day of departure.