In search for a Sarmatian etymon for his invented Iazigyan word **far-ang 'enemy, one of the others', which, according to him, might have been used by the Iazyges in Pannonia (early centuries CE) to designate the Romans and the Germanic tribes who entered their service, and that would have been subsequently adopted by the latter tribes as their own self-designation, thus, allegedly becoming pre-Frankish **frang > Germanic frank, Torsten now writes:
> [T]he /r/ -> /l/ thing seems to be later than Alanic.
and
> [Ossetic denominative] suffix -ag... There's your suffix.
The /r/ -> /l/ sound shift in Scytho-Sarmatian languages seems to belong to the Middle Iranian stage of North Iranian, as is attested in the Pontic Insctiptions. Of course, nobody knows the *exact* date at which this sound shift was complete.
The Ossetic denominative suffix -ag is thought to derive from the very productive Old Iranian suffix -ka through the Middle Iranian forms *(a:)ka and/or *(-ya)ka (where /-*a:-/ and /-*ya-/ belong to the stem rather than to the suffix itself).
The nasalized suffix **-ang you propose for your **far-ang did not exist in Scytho-Sarmatian.
Therefore, your invented Sarmatian ethnonym should, in case, be reconstructed as **fala:k(a) or, at best, **fara:k(a). Would you derive Germanic 'frank' from such a word?
Regards,
Francesco