The screenshots show ATM10 SKY being translated into Japanese.
Open the gear button → LLM Settings. Choose your provider, API key, and model, then Save Settings. Get an API key if you need one. Your provider charges for API usage.
Open Quests → Select Profile and choose your modpack's game folder (the one containing mods and config).
Choose the target language, Scan, check the files you want, and click Translate.
Choose Standard API for a quick result or Batch for a lower-cost bulk translation, then start. Batch may take up to 24 hours.
When translation finishes, launch Minecraft, set the game language to your target language, and open the same quest. Restart the game if it was already running.
Want item names and descriptions too? Repeat in Mods, then enable the generated resource pack in Minecraft. Use Guidebooks for supported in-game books.