V3.3:

• Add french translation package to the project:

  composer require ezplatform-i18n/ezplatform-i18n-fr_fr
  

• Set Back Office language to French
• Edit Page Builder Block

Result:
'Valider' and 'Discard' buttons are shown

Should be:
'Valider' and 'Annuler'

Note:
Same applies for ezplatform-i18n/ezplatform-i18n-de-de
and possibly for othe languages.
Additional there is a key 'cancel' in https://crowdin.com/translate/ezplatform/1282/en-de?filter=basic&value=0 and https://crowdin.com/translate/ezplatform/1282/en-fr?filter=basic&value=0