is there a possibility to generate a report in RME 4.2.0 containing the media type of an interface? Something like the "Type" column in "show interface status"?
In general this is not possible. RME uses the ENTITY-MIB to build inventory for most devices, and this exact type of information is not available. The detailed device report will show you the port type as seen from the ENTITY-MIB (e.g. cevPortNIC100 for a port that shows a status type of 10/100BaseTX). It will also show you the current configured interface speed.