Translation Sync Bug: Newly Added Nested Paragraphs Not Syncing in Multilingual Nodes

Problem/Motivation

In multilingual nodes that use nested Paragraphs, paragraphs present in the source language at the time of translation creation are not fully synced if additional paragraphs have been added. Although later changes in the source node trigger an automatic sync, any paragraphs added before or during the initial translation creation remain unsynced. This creates inconsistencies between the source and its translations, particularly affecting complex nested structures.

Steps to Reproduce

1. Create a multilingual content node (e.g., a Donation page) with nested Paragraphs in the source language.
2. Add several paragraphs (including nested paragraphs) to the source node.
3. Create a translation (for example, French) for the node. The paragraphs present at that moment will be cloned.
4. Add additional paragraphs to the source node after the translation is created.
5. Observe that these newly added paragraphs are not automatically synced to the translated node.

Proposed Resolution

As a temporary workaround, delete the affected paragraphs from the source language node and recreate them. Recreating these paragraphs forces the sync mechanism to trigger, automatically propagating the new paragraphs to all existing translations.

Remaining Tasks

• Investigate and identify the root cause in the Paragraphs module's translation sync logic.
• Develop and test a patch to ensure that all paragraphs, including those added before or during translation creation, are correctly cloned.
• Verify the fix across various scenarios and nested paragraph structures.
• Consider additional UI enhancements to manually trigger sync if needed.

User Interface Changes

No immediate UI changes are required. However, a future enhancement might include adding a "Sync New Paragraphs" button or a notification system to alert editors when new paragraphs have not been synced.

API Changes

There are no changes required to the public API as this issue pertains solely to the internal sync logic.

Data Model Changes

No modifications to the data model are necessary. The problem lies within the synchronization process rather than in how paragraph entities are stored.