Hello,
Thank you for answer.
Your test workflow it’s not correct.
“Copy from original post” copy only content, without fields.
To achieve step 2 (Xeng — relations field —-> Yeng (“copy” setting in WPML)) you must set “copy” option in WPML -> Settings -> Custom field translations -> Relation field.
Then the connection of automatic connection to another language version will work. And thanks to your plugin, a two-way relationship also will work.
But last case, the bidirectional relationship between the post in the second language version will not work.
Regards!