I don't think this has already been submitted (at least, a search on the last 5 years didn't give much results).
What I'd like to suggest is an easier way to translate mIRC in languages other than English.
Of course, you can use mIRC's scripting abilities to change the so called "Command menu", but this isn't the only thing that we should be able to translate.
I'm also well-awared that there is probably some DLLs around the net that will allow you to achieve this, but IMHO, this should come as part of a basic, clean copy of mIRC.
I think an easy way to do this would be to include an XML parser in mIRC and loading labels for menus etc. from an external XML file.
Sure enough, the strings in English should still be hard-coded in the program (we don't want menus to go "blank" when some strange user decides to get rid off the languages/English.xml for example...)