FWIW (for those trying to get their bearings about the Proto-Iranian root), Wiktionary points out: “From Proto-Indo-Iranian *Hsuĉráwas, from *Hsu- (“good”) +‎ *ĉráwas (“fame”). Equivalent to *Hhu- (“good”) +‎ *ĉráwah (“fame”). Cognate with Vedic Sanskrit सुश्रवस् (suśrávas, “famous”), Ancient Greek Eὐκλῆς (Euklês).”

We can count numbers 1 to 10 on our fingers now; are you claiming that the Romans did not? I can understand you dismissing the specific diagram in the OP as fantastical, but that still leaves the question unaddressed of how Romans counted on their fingers. (Did they do it exactly as we do?)

Incidentally, a very similar culture of hospitality was (is?) present in Indian culture too (including many examples of this "theoxenia" in the epics/puranas, and elaborate rules of hospitality in the dharmashastras); probably yet another example of the broader Indo-European culture.

What makes you say that "Prakrit definitely predates Sanskrit"? It's the other way around: Prakrit can be traced back to Vedic Sanskrit at any rate. Also, Brahmi is a script (used for writing Sanskrit and Pali, among others), not a language. And Pali is a kind of Prakrit too (Magadhi / Ardhamagadhi), which just acquired distinctive status for historical reasons (extensive use in Buddhism, etc). (Finally, it is debatable whether Sanskrit and the Prakrits (especially the early ones) should be classified as different languages or as different registers.)