I'm English and cannot speak for other EU countries because I have never experienced them from an aviation viewpoint. Also, it's 11 years since I retired and my ex-colleagues keep telling me that everything has changed beyond recognition. However, during my 30+ years in English ATC I cannot recall too many incidents of bad R/T either by ATC or pilots.
Back in the 70s the east european and one or two southern european crews did not speak much english but they got by. Russian aircraft, e.g. TU-104, had very poor radios not helped by (I think) throat mics. By the time I left everything seemed A-OK. In all my ATC time, including time abroad, I found US pilots exceedingly good to work with and the USAF beat everyone else hands down. But that's just my personal opinion.