As of now, what I am getting about Rajat's character...that earlier he was a normal human but due to curse, he completely transformed in to a nevla, so where this icchadhari thing comes into play. If due to this icchadhari thing, he can still easily transform himself into human form, than what's the purpose curse is serving.Their is no real use of him being cursed.
To me, article itself is somewhere contradictory, first they say, he will be an icchadhari nevla but than this line "Rajat's character is cursed and will be seen trapped in a mongoose's body...the word trapped...he will be seen trapped in a mongoose's body, as far i can understand, he can't turn into human as per his wish, as being trapped due to curse effect.
and now this line...The only way for him to break the spell is to kill an ichchadhari naagin...so as to remove the curse effect, he has to kill an icchadhari naagin.
So, I think he may be just a cursed human who turned into normal nevla, no icchadhari thing and after he breaks the spell, he will again turn into normal human.
just my guess😆...what's your take guys...Is it possible😉