You get no credit for having night privileges as part fo your FAA certificate against an EASA night rating. You will have to complete the 5hrs flying in accordance with the EASA syllabus. The FAA certificate does not state night privileges as its a built in privilege with the FAA but an added one under EASA.
We encounter this all the time in the school with FAA to EASA conversions. The number of CPL applications we have seen rejected because of it..........