Could it be possible to edit these into their "real life" counterparts? I've found which files they are in, should I just try to edit them or has someone tried this alredy and failed?

Also, how can I edit the referee and competition names?

Thanks in advance.

for your first question...im not sure mate..
but for your second...use the hex editor

for the second you can d/l ready made ref names here (http://frutsel.terrainhost.com/frutselapp/dump/Mayor/PES3/referee%20names.rar)