[Bug] Simplified Chinese kanji glyphs appearing in Japanese responses

Bug Description
Title: Simplified Chinese characters leaking into Japanese output (字形 mix-up)

Description:
When responding in Japanese, Claude occasionally renders individual kanji in Simplified Chinese glyphs instead of the correct Japanese forms. In my session the word "審問官" was output as "审问官" (with 审/问 in Simplified Chinese), and it was inconsistent within the same response — other instances in the same message used the correct Japanese "審".

Example:

• Incorrect (Simplified Chinese): 审问官
• Correct (Japanese): 審問官

Affected character pattern:
Words where the Japanese (新字体) and Simplified Chinese glyphs diverge are at risk, e.g.:

• 審 vs 审
• 問 vs 问
• 検証 vs 检证
• 発見 vs 发现
• 価値 vs 价值
• 戦略 vs 战略

Expected behavior:
Japanese responses should consistently use correct Japanese kanji (新字体). Simplified/Traditional Chinese glyphs must not be substituted, and glyph choice must be consistent within a response.

Environment:

• Claude Code, model: Opus 4.8 (claude-opus-4-8)
• Configured response language: Japanese

Severity: Low (cosmetic/orthographic), but it undermines trust in output correctness for Japanese users and can corrupt copy-pasted text.

Environment Info

• Platform: linux
• Terminal: kitty
• Version: 2.1.193
• Feedback ID: 4ddcedfa-ac6b-4c1e-a2cf-d7c587281641

Errors

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