The question which form your nagyi are is easily to be answered as “not Kuantan” if the coloured band in the tail is correctly shown as to be not a pure white. On the other hand, in other photos there are the prolonged spines that extend over the edges of the fins (especially the tail) clearly to be seen; a feature not to be found in the Cherating-form. Nevertheless, these two forms do not indicate the full range of nagy-forms.
The solution is that there are more intermediate forms than those two. We had, some years ago, for instance an intermediate form caught by Allan Brown. In the years from 2010 most nagyi that came by the trade were called “Pekan Nenas”, and did more resemble the classical Kuantan than the rather isolated Cherating. The home range of nagyi near the eastern coast of the Malayan peninsula is quite extended, and near the northern and southern end they differ clearly. But there are intermediate forms indicating that these are not different species but variants of one species only.
We are by far not fully informed about that variety. The scientific description is fully based on the Kuantan form; it is valid but not very elaborated. My friend Dietrich Schaller (the author) wrote it many years ago not knowing about that variety. Hallmann was the first who caught the Cherating form and rightly called it “Cherating”, but in the meantime other intermediate forms have come to our knowledge.
Before naming or even defining new forms we should exclude two sources of failures that are very often made today: different age and mood of our fish and the changing impact of the art of photography, light, and the technical differences that belong to cameras and the equipment, including the subjectivity of the displays of our computers. It is very obvious that the first is involved in this case, too, as you compare the first pictures and the last. Not seeing the living fish one is incapable to exclude the second type of possible failures.
My advice is to see our Paros as a wonderful example of open questions: Science far away from final truth, and the hobby as its necessary supplement in a continuing process. Most aquarium fish do not expose such an openness; they swim around and enjoy their possessors until they die or (mostly) are exchanged against new species. We are more deeply interested in fish that still pose riddles and unsolved problems, in some cases of species identification, in others (as here) in the identification of forms hitherto named, but not as the end of the descriptive pipe, but as its beginning only.