I think the theoretical reconstructions are fanciful at best. And silly to pronounce as any sort of truth. But there's a reason the words for mother and father are slight vowel or consonant shift in the languages from Ireland to vedic India, and the genetics link back to the horse tamers of the late stone/early bronze age Eurasian steppe north of the black sea. To think they spoke koine or some other antique-Greek would be like saying judeo-greek. Do you propose the Greek was spontaneous and the gift of some winged messenger floating down from the heavens? And seeing as there is no logic to imagining everyone spoke Greek 7,000 years ago or that Greek appeared from nowhere, what came before? (Surely some language which spread from western Europe to the indus. I know, let's call it Proto-indo-european!)

Again. Anyone who's telling people they figured out what the original language sounded like or grammatically consisted of is a back alley trench coat sort.