CJK stands for Chinese, Japanese and Korean. Each language renders very differently from Latin, and naive layout breaks in predictable ways.
Density and breaks
CJK characters carry a full word per glyph. A four-character Japanese title can mean what takes ten English words. Lines break between any characters, not on spaces. A simple "wrap on space" algorithm produces lines that end mid-word.
Font choice
Use a font designed for the language. Noto Sans CJK is the safe default, with separate weights for Simplified Chinese, Traditional Chinese, Japanese and Korean. Mixing the wrong variant gives subtle but noticeable wrong glyphs.
Line height
CJK glyphs are tall. A line-height that works for Latin produces overlapping lines in Chinese. Add 10–20% to the line-height value for CJK locales.
Punctuation
Periods and commas are different glyphs in CJK ("。" "、" not "." ","). Auto-translation that copies Latin punctuation looks wrong. Most translation models get this right; double-check anyway.
Hangul has its own rules
Korean uses syllable blocks. Spacing between blocks affects readability. A monospaced or "shrink-to-fit" approach often produces unreadable Korean. Allow the line to wrap naturally instead.