Do you know whether the author has talked about the namarupa formation in vinnana via javana citta?
Not sure. In initial 150 pages, I haven’t encountered formation via javana citta. Perhaps in latter part of book, which I have only skimmed through thus far.
so I presume he doesn’t distinguish then between vinnana and kamma vinnana and/or sankhara and abhisankhara. Have you come across anything?
So far upto 150 pages, there is no differentiation.
It is possible that this is faulty English translation. Author might have not intended the meanings written in English translations in his original sinhala treatise.
UPDATE: I performed a quick search author differentiates between saṅkhāra and abhisaṅkhāra, also, viññāṇa is called defiled consciousness in latter part of book.