In the smartforms you can create the text module for each and every word you need to display in the French language. The you need to have some condition check which language text need to be display.In this case you can display the text based on the user’s login language.you have to have sy-langu checking in the smartform.
Base on the language it will display in the smart forms.
Note:You need to select the appropriate language for your text module when you are creating.
Hope this will help to you.