To sync the product attributes, there are two options:
1.-
- Edit the product in the original language
- Make a small change in the content or in the attributes
- Save the changes and update the translation
2.-
- Go to WooCommerce -> WCML -> Status tab
- Click on the Troubleshooting link (bottom right)
- Select the options to sync the attributes and variations
- Click on the Start button and wait for the process to finish
So my issue isn't relate to variations. But parent product attributes. I've added some to improve google merchant center quality. And want to synchronize them between all languages.