Step 1: Close all warhammer 40000 darktide game processes or tabs
Step 2: untick “read-only” checkbox from file properties and save
Step 3: open user_settings.config as notepad
Step 4: change “en” to “es” and perform “ctrl + s”
Step 5: tick “read-only” checkbox from file properties and save
Step 6: open the game.
PS: Language changes will not affect the game launcher, need to verify at in-game menu.