Mommsen and Dacian name

In the edition of "Romana et Getica" from Jordanes, edition
redacted by Theodor Mommsen, we find more forms for the dacian
Zalmoxsis, Taraboste and Burebista.

Zalmoxe

appears as zalmosen, zalmonen, zalmozen, dalmoxem, zalimoxem

Taraboste

appears as tarabostereos, zarabostereos, straboste eos,
thorabostes eos

Burebista:

appears as buruista, burusta, boroista, byrruisia boscurta

Question: how or why are the forms Burebista, Zalmoxe and
Tarabostes seen as the really form of the words?

Sure, I do not ask useless, I ask because I try to make some
connections with actualy words ( if any ):-))

regards

a. moeller