How do I get an LLM to write natural Haitian Creole instead of French-flavored Kreyòl?

A few techniques that measurably help:

1. Show, don't just tell. Put 3 to 5 short examples of the Kreyòl you want in the system prompt, written by a native speaker, in your app's tone. Models imitate examples far better than they follow abstract style rules.

2. Be explicit about orthography. Name the standard orthography, used by the Akademi Kreyòl Ayisyen and in schools, and list the errors you keep seeing:

Write in Haitian Creole using the standard orthography.
Use "ki jan", not "comment"; "kounye a", not "maintenant"; "yo" as the plural marker.
Do not use French spellings (write "kesyon", not "question").
Prefer everyday spoken vocabulary over formal French loanwords.

3. Don't translate from an English or French draft. Asking the model to "write in English, then translate" produces translationese. Ask it to answer directly in Kreyòl.

4. Pick the model by testing. Kreyòl quality varies a lot between models and versions. Run the same 30 to 50 prompts through each candidate and have native speakers rate naturalness blind (without knowing which model wrote what).

5. Keep a glossary for domain terms (technical, medical, financial) and include it in the prompt. Consistency matters more than any single "perfect" word choice.

6. Collect feedback. A 👍/👎 plus an optional "better phrasing" box builds a dataset of preferred Kreyòl that you can reuse as examples.