Dear Tharpachozang,
Neither the Mahāniddesa nor the Cūlaniddesa have, to my knowledge, been translated into English. The reason is probably two-fold. First, much of the Niddesa consists of glossaries, lists of alternative Pali words. It is not easy to know how to translate such glossaries into another language. Second, the structure of the Niddesa is unattractive. It is not really a commentary, but more of a mechanical glossary on every word, but rarely with any illumination of the meaning of the word in its narrative context.
As an experiment, I recently started a translation of the Cūlaniddesa on the Khaggavisāṇasutta. I think it is possible to translate, but I am not sure if it would make sense to someone who did not already know what the Niddesa was like and why it is like that. Has anyone else tried translating it?