For on Nintendo Switch, language packs are available as separate, free DLC rather than standard in-game updates. If you are using the NSP (Nintendo Submission Package) format, you must install these specific DLC files alongside the base game and latest update for them to work. Available Language Packs
Legal and safety reminder: Distributing or downloading copyrighted game files without owning the original is illegal in many jurisdictions. Installing NSPs typically involves bypassing console protections; this poses security, stability, and warranty risks. diablo iii eternal collection nsp language p upd