You can change the source language of strings in WPML via String Translation.
If you’re using a theme or plugin that was developed in a language other than English, the source language of your strings will appear incorrect in String Translation.
To change the source language of individual strings:
- Go to WPML → String Translation.
- Select the strings you want to change source language for.
- Click the Change the language of selected strings dropdown and choose your new source language.
To change the source language of all strings coming from a plugin or theme:
- Go to WPML → String Translation.
- Scroll down to Utilities and expand the Set the original language of themes and plugins section.
- Click Set the language of text-domains and choose a new language for your domain.