Oliver had 3 appointments in the CL Group matches in Lyon, Barcelona and Moscow so it's not as if he's been ignored. And I'm not aware of any great controversy in any of those games although there were a lot of YCs in one of them as I recall. Taylor has had 4 matches, some more high profile, so I accept that he is seen by UEFA / Rossetti as the slightly more accomplished referee at the moment. It's unfortunate perhaps that it was an Italian team that were involved in that Real Madrid game, although the consensus on here and with former English International referees was that the penalty and red card were correct.
Oliver has more years to develop further so it will be interesting to follow their respective careers with UEFA, FIFA and the PL.
I didn't see the game last night but shall look for Herr Zwayer's future appointments.