How about striping the broken Hangeul characters from that font and leave the rest as it is? (I have no experience with fonts, but it sounds easier than creating a new font) I think, most ppl could accept Hanja rendered with a Chinese font in en_US (or de_DE in my case), as long as they are readable. But having Hangeul in this state in the default installation is very unsatisfying.
How about striping the broken Hangeul characters from that font and leave the rest as it is? (I have no experience with fonts, but it sounds easier than creating a new font) I think, most ppl could accept Hanja rendered with a Chinese font in en_US (or de_DE in my case), as long as they are readable. But having Hangeul in this state in the default installation is very unsatisfying.