It is very easy to translate a popup to several languages for your WPML site.
You only have to have an original popup in your main language and then we will duplicate that popup to modify the texts to the other languages.
Follow these steps:
This is the popup that we will use as an example and it is in the English language.
Then set the URLs where you want to show this popup, and exclude the URLs of the other languages.
Then edit the texts to change them to Spanish language.
And we also add the URL where we want to show the popup. In this case the URLs of the Spanish language.
That’s it, you can repeat step 2 to use the popup in any language of your WPML site.