Problem: The client is experiencing an issue where WPML replaces German strings with English strings in custom fields when a translator updates an existing post. This problem occurs across multiple post types and is suspected to be related to the Advanced Translation Editor.
Solution: We recommend setting the affected custom fields to "copy" so they are not editable in the translation editor and are always copied directly to the translation. This should prevent the fields from being overwritten. Here is a guide on managing custom field translations: Translating Custom Fields.
If the issue persists, consider disabling the WPML editor and continue using the manual method for translations. Alternatively, if using the Advanced Translation Editor, ensure that numerical values are correctly configured for translation by adding a specific code snippet to the functions.php file of your theme. More details can be found here: Translating Numbers.
If these solutions do not resolve the issue or if they seem outdated or irrelevant to your specific case, please check related known issues at https://wpml.org/known-issues/, verify the version of the permanent fix, and confirm that you have installed the latest versions of themes and plugins. We highly recommend opening a new support ticket for further assistance at WPML Support Forum.