No foreign-language support is documented for 덕가산; only Korean is confirmed.

• Korean is the only language confirmed as supported.
• No English, Japanese, or Chinese support is listed.
• Multilingual signage status is not documented.
• No audio guide, sign-language guide, or large-print guide listed.
• No localized name or address is available in English, Japanese, or Chinese.
• As an outdoor mountain site, on-site staff assistance is not documented.

Based on language_support.korean (true) with all other language_support fields null; canonical_name_en/ja/zh_hans and address_en are null; accessibility.audio_guide, sign_language_guide, and related guide fields are all null.