Can I set the width value of each letter?
Yes, each letter has it's own size in font file.
I see your font have 128 bytes, so i think that should be implemented same way as russian font:
Chars 0-127 is the 1-st part of ASCII table, it's for english and common part for all other languages. And the 2-nd part is russian: 128-255.
So, i think korean charset can be released something like tha way:
1. Unpack font10x.fnt from war2.
2. Copy your letters with codes 128-255 replacing the existing letters if needed
3. Build appeared font again with War2FontTool
4. The most interesting question: how to sync your korean keyboard with korean font? Try to type each korean letter opn the keyboard and check which latter appears on screen. Not sure about korean, bur in russain there have been absolute mix: letters with some very strange order.
5. Reorder your letters to make them similar to keyboard.
6. After that you can try to rewrite text strings in game.
Oh, i forgot the main thing:
You should use exactly the same colors in your .bmp images as in images exported from the english font. And also the same bmp format.
For example, color code 03 for the main color, color code 05 for shadow, etc. Should be possible to auto convert colors for all your images automatically somehow, i hope so.
Use exported bmp from font as a template.