Specify the language for speech and narration
A direct request can cover both parts: 'Use Spanish for the dialogue and narration.' For a bilingual scene, explain which parts belong in which language, such as dialogue in one and descriptive passages in another.
Keep names of characters and important locations stable. If the same name receives a different translation in each message, the conversation may start treating one subject as several unrelated people or places.
Check the definition as well as the model
Our models differ in their multilingual strengths. Try an everyday exchange in the language you want using a model available to your plan. That small test can reveal unnatural wording before a longer story depends on it.
Repeated English examples in a definition may draw the character back toward English. If it is your character, adapt those examples to the intended language. Otherwise, look for a character whose existing description is closer to the conversation you want.
Correct a language change without retelling everything
If a reply shifts languages, state the preferred language again and continue from the current scene. A focused correction is usually enough to address the language choice without repeating every event in the plot.
Generated wording can still mishandle dialect, specialized terms or an ambiguous name. Treat it as character dialogue, not a certified translation. It should not be relied on as authoritative legal, medical or financial wording.
Questions
Can I request Spanish, German, Arabic or Japanese replies?
You can request those or other languages and try a supporting model available to your account. Results depend on the model and character instructions; translating the interface alone does not ensure consistent replies in that language.
What can make a character return to English?
The greeting, definition, dialogue examples or recent messages may favor English. Repeat your preferred language and check those instructions wherever you have permission to edit them.