How to translate notification on iOS

Hello here !

I am working with an agency that provides the API for my app. The notifications are working great and I am using the expo-notifications library with their custom FCM & APN implementation. But on iOS they just send me a translation key as notification message like MY_KEY.
So my question is, how can I change the content of the notification on iOS to translate the key before the notification is displayed ? And is it possible ?

P.S. : On android they send me a preview of the message so everything is fine