Hi,
I already found a solution.
Instead of a text box, you use this widget which let you write PHP code:
https://www.hongkiat.com/blog/execute-php-in-wordpress-post-page-and-widget-sidebar/
Then, in the widget, you write this:
<?php
if(ICL_LANGUAGE_CODE=='en'){
print("English text>");
}
if(ICL_LANGUAGE_CODE=='es'){
print("Spanish text>");}
}
?>
I hope it will help someone:)
Regards