That is not acceptable in my field anyway. In linguistics many have only worked backwards to reconstruct retrospectively what Indo-European used to be and so on. And it reached a dead end: Proto Indo European.

That goes against the basic principle of Darwinism: we have to descend from the past to the present. We cannot and shouldn’t reconstruct missing links backwards but at best reconstruct them descending from what is known about before and descend from there to what we know exists after the missing link.

In linguistics the only real method is phylogenetic, descending from what we know about “language” or communication of species before the human species, then deduce from the physiology achieved by mutations selected for any reason (in our case to enable Homo Sapiens to become a long distance fast bipedal runner) and what these mutations can produce linguistically and yet Homo Sapiens has to understand, invent, create from these means given to him for other reasons than speaking. Always descend and not go backwards.

Check https://www.academia.edu/33739390/Cro-Magnons_Language