Next.js CJK i18n Typography Patterns

Problem

When adding CJK (Chinese/Japanese/Korean) language support to a Next.js app with next-intl, several non-obvious typography and UX issues arise that don't exist with Latin-only locales. CJK glyphs are visually larger, denser, and have different spacing characteristics than Latin characters, requiring locale-aware adjustments that go beyond simple translation.

Context / Trigger Conditions

• Next.js app using next-intl with CJK locales (zh-CN, zh-TW, ja, ko)
• Custom CJK fonts loaded via CSS :lang(zh) selectors or CSS custom properties
• Headings or large text that looks oversized in CJK compared to English
• Latin text (signatures, brand names) unexpectedly rendered in CJK font
• Locale switcher redirects back to old locale after switching
• Short CJK headings wrapping to multiple lines unnecessarily
• Route-based visibility logic (hiding elements on certain paths) breaking on locale-prefixed URLs