I have met few Bengali Writer and family member of writer who had died. .
Their main concern about commercial use of their text, if derivative in translation, it will be not any issue of them. They have no issue for published at Wikisource. So what should be the licence and how we published in Bengali Wikisource?
But they are ready to release all their book at Attribution-NonCommercial-NoDerivs 3.0 Unported (CC BY-NC-ND 3.0). https://creativecommons.org/licenses/by-nc-nd/3.0/ or any equal license.