Some quick notes:
It's not "Imperium Romanum Occidentale/Orientale" it should be "Imperium Romanum pars Occidentis/Orientis"
Hunnu - This should actually be Huna, based on 4th century Chinese and Iranian sources
Sabiroi - This word is actually Oghur Turkish (Hunnic) with a Greek ending tacked onto it, from Priscus. I don't think we know what the plural is, although it might already be in its plural. You could try and see if there's a parallel with a modern Turkish dialect in the ending, but I don't know how Turkish declines its nouns. The Chuvash are allegedly remotely descended from the Sabir Huns but I don't know if the word Sabir exists in Chuvash (a quick look at their dictionary doesn't list it).
If you can't find anything, could always just go with Sabir Huna.
Ostrogoths/Visigoths - Technically neither of these names were used until the late 5th century, the Visigoths didn't take up the term Vesigetae until after 455 or so, and the Ostrogoths didn't even form until the 480's, out of the old Amal Goths. So it might be best to do "Vesi" and "Amali".
For the various Eastern factions, you should check out this map, all the names are in Middle Persian (what the Sassanids Spoke):
http://iranpoliticsclub.net/maps/ima...0600%20Map.jpg
E.g. the Afrighids are Xvarazm (Chorasmia in Latin, Khwarezm today). Persia is Pars, Sughdia is Gilan, Parthia is Part, Sugd is Sogdia, Marg is Margiana, etc. etc.
The Greuthungi should be the Tetraxite Goths (Tetraxitae) who lived in the Crimea until the 7th century AD.