Microsoft Windows does not support control codes in INI files. this is not a mIRC problem but a 'feature' in Windows. nothing you can do about it except using $chr() or $encode/$decode.
I used to use $decode uptill the moment it was locked by default :-[ it worked perfectly but unfortunately I can't use it anymore since users have to unlock $decode for it to work...

it goofed up for me all the time while trying to use control codes in ini files, usually by not returning the entire lines.