Updates one language's translation of a question. custom_actions is the only field written; question_text, recording_filename and recording_uuid are accepted by the schema and ignored, and sending a language that differs from the path is rejected with 400. Validation currently rejects any non-null custom_actions, including an empty array, so the only value that writes is null — use POST to replace a translation's actions. No audio is regenerated and the call routing is not republished here.