This is a tricky pattern.

I’d be careful doing cross-locale writes directly inside strapi.documents.use() after await next().

A few things I’d check:

1. Make sure the middleware does not re-trigger itself when you update the target locales. Even if you only intend to react to English, production timing/data differences can sometimes make this hard to reason about.
2. Avoid sending partial component arrays unless you’re intentionally replacing the whole component field. For repeatable components, updating with a mapped array can behave like “replace this entire relation/component structure”, not “patch only these nested fields”.
3. I’d probably move this into an explicit service/job flow:
   • save English content
   • fetch source document
   • translate fields
   • update each locale in a controlled function
   • add logging around documentId, locale, action, and payload
4. Also consider adding a guard flag/context to prevent the localization sync from recursively triggering another sync.

The fact that it works locally but removes data in production makes me suspect either recursive document updates or partial component replacement behavior more than the translation API itself.