A couple of years ago I did look into mIRC support for Unicode, and the differences between mIRC's use of UCS-2 (which is a subset of full unicode UTF-16) and full Unicode, and I started to write a utility script which imported a unicode definition file
and used that to provide a full range of Unicode identifiers. But I had to stop work on it due to other real-life priorities, and haven't had a chance to go back to it - but it does give me an insight into the difficulties in this area.
To fix this properly would require mIRC to switch its strings from UCS-2 to UTF-16 - and this might have some general backward compatibility issues.
So I imagine that this is a really non-trivial change.
That said, I would be happy to share either my design thoughts for the identifiers I was planning to provide or even the embryonic code I created if Khaled or anyone else is interested.