I know a several people who collect Tolkien in translation, but no one who has a more extensive collection than Wayne Hammond and Christina Scull — some 170 linear feet altogether. That’s about half the length of an American football field! So I decided to ask them about the Marathi question. Who better to say whether it’s real but rare, or merely a tall tale?
Wayne told me that while writing their Tolkien Companion and Guide, he and Christina contacted Tolkien’s British publisher, HarperCollins, to inquire about the existence of the rumored Marathi translations, and they were told that there was no record of an agreement for any such translation. If the translation exists, it is therefore a pirate, and HarperCollins had only heard of its alleged existence from a third party source. Wayne and Christina believe that the HarperCollins website was the sole public source attesting the existence of a Marathi translation, and like me, they’re inclined to doubt its existence. 
Even if there is a pirate translation out there somewhere, no one I know has ever seen it. It’s probably no more than a fabled figment of the imagination. I consider the question settled.
 Paraphrasing from private correspondence.