i believe internet config really only does it for ftp-originated content when the ftp transfer was done with a webbrowser who supports this, which is why i dont even have it installed since 15+ years.
the settings in my file exchange controlpanel...
do work.
to make sure that there is no influence by quicktime or stuff it deluxe i just tried .asp->dreamwaver and .cpp->codewarrior, which i put on my ftp server of my website and then downlaoded again with fetch - and those files work as they should.
however, if you prefer to have the BNDL´ed icons visible, changing the creator/type manually is not a bad idea anyway.
if it was not you i would now also add that you have to check "open unmapped files on local disks"