IBM made some changes in their V5R3 implementation of CPYFRMIMPF. It turns out that they are really starting to obey the CCSID set for the file, so if your system value is set to 65535 (binary/no translation) then you'll really get no translation. Read the below APAR for an explanation, and the PTF that's available to restore the V5R2 behaviour.
IBM eServer iSeries Authorized Problem Analysis Reports (APAR): II13784
IBM eServer iSeries Recommended Fixes - Database: SI16664
PTF SI16664 - Operating System/400
PTF/FIX #: SI16752 - Operating System/400