I haven't read that specific book, however, I do recognize one of the authors. Grigory Maximovich Bongard-Levin was a very well known academic and historian who specialized in south and central Asian history. He wrote a number of books on ancient India. The Mauryan Period in particular was his specialty.

He won a lot of awards and honors, including the USSR State Prize. The Government of India also recognized him with the Padma Bhushan, which is India's 3rd highest civilian award, for his contributions to research in Indian history.

I don't know the other authors, but Bongard-Levin's name carries a lot of respectability on that topic.

This is a translation of a book published in Russian six year prior. Mir Publishers were a house mainly translating foreign science and scholarship into Russian but also, as in this case, the other way round. I haven't found a review of this particular book on jstor (although there are five papers that cite it), but searching for it's authors names (in particular Bongard-Levin) reveals they were respected by colleagues abroad.

No, it's not a bunch of hacks, if that is what you're asking.