The generated descriptions are returned as english, so we need to use separate translation providers to translate them to your websites local language.
Google's Cloud Translation Api docs.
pip install wagtailaltgenerator[google_translate]
The Google Cloud Translation Api uses google-cloud-translate and are typically authenticated using Application Default Credentials for authentication.
You can authenticate locally with the Google Cloud SDK, on production with either the built in credentials (if you already run on Google Cloud) or with a Service Account key file.
You also need to activate translation
ALT_GENERATOR_TRANSLATE_TO_LOCAL_LANG:True