Common custom fields across translated posts

In xili-language data model like in wp, each post is independent with his own language (taxonomy) and his own custom fields (post_meta)…
When creating translation, if you need to copy fields of the original post to help you to translate in the target post… you must create a special function with the filter/hook called when saving the new post… named save_post

(today, xili-language assigns taxonomy to the target post if the original has, by example, categories)…

Add your customized filter in your theme or your plugin – don’t modify the plugin – you will loose when updating plugin…