I don't see anything illegal about it. The guy has made a script and says it is copyrighted.. is that illegal i don't think so.
And Khaled has put .dll support into mIRC, with no clear guidelines as to what we can or cant do with it. The guy has changed some menu text into his native language. So what? We are presuming it's a DLL that's done it.. Maybe it's his OS that interprets it?

And if not, Just go to mircscripts.org or scriptaz and check out all the .DLL that modify menus etc. Im sure other scripts like paIRC, aIRC , etc, all modified mIRC with .DLL's and had (c) on there website. To single out this one script because it is'nt english, and isnt as popular, that isn't really fair. Let's start waving the dirty end of the stick at the people who clearly break the license agreement by distributing modified/hexed executables.