Thanks to your guidance, I was able to view Korean text in LibreCAD. Thank you.
However, as stated in the manual, I noticed that for non-English characters, the font strokes are displayed only as hollow outlines rather than filled shapes.

Although I haven’t searched extensively, it seems that support for Chinese characters and Korean is still not sufficient.
I hope that support for Korean will improve further in the future.
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EDIT
Typo: LLF -> LFF