When using the stable widget, deleting a translation with a non-default language source can delete paragraphs if that translation's source is the non-default language.
- Configure a translatable site with 3 languages (EN, EN-GB, FR)
- Create a translatable paragraph type and add to a content type
- Create a node in EN, with a paragraph
- Create an EN-GB translation and translate the paragraph
- Create a FR translation, but set the source language to EN-GB. Translate the paragraph
- Delete the EN-GB translation. The paragraph will be missing from the FR translation
I think it would be possible to prevent this in paragraphs_asymmetric_translation_widgets_entity_translation_delete() but there seems to be a problem with the underlying data model and fixing that should fix this issue as well. See
#3412626: Difference between the 'Paragraphs (stable)' widget and the 'Paragraphs Legacy Asymmetric' widget →
Needs review
1.0
Code
I agree that the root problem is the duplicate data created during translations.
Regarding the patch above, it has two issues:
1. For paragraphs that have only 1 default language, trying to remove the default translation will cause an exception
2. Removing a translation without saving the paragraph doesn't do anything