It is very likely that Titler is unable to properly print that particular font.
A user had similar issues with another Asian font, where only some characters would work, and others had the boxes. In that case, we found another, similar font (cannot remember now, from which foundry), and that one worked perfectly.
Adobe programs, in general, and Titler specifically, are very, very sensitive to fonts. Any corruption will case issues, and even crashes. Other fonts, if not well-written, or incompatible with the Adobe program, will either not work, or display what you observe.
I would search the Internet for another version of that font, and I would then limit it to just major foundries.
PS - I have encountered several fonts, that work well in other programs, but just do not work/display in Adobe programs, such as many in the Isabelle and Isabella family.
Thank you! I selected the text and switched it to about thirty different fonts that were listed in Premiere Elements. Finally, I found Batang, which is an old standby that works for me in Word. I tried it, and presto change-o, my Korean looks like Korean. What a huge relief. Thank you again! I never would have tried it without your advice.
You are most welcome, and glad that you found a substitute.
If your problem is solved, then you might want to look over this article: http://forums.adobe.com/thread/1058744?tstart=0
Good luck, and happy editing,
Update: For 2016 fonts on CC it's- HeadlineA, PilGi & Nanun. Just in case anyone else wants to write in Korean