I've generally felt that the Vaulters had an Eastern European vibe going to them, along with the frequently mentioned "Viking" feel to them. 

Well I've just found out that žiema means "Winter" in Polish (https://en.wiktionary.org/wiki/%C5%BEiema). For instance consider this painting: https://lt.wikipedia.org/wiki/Vaizdas:Ziema.jpg 

Does anyone with a Polish background, or from elsewhere notice details of the hero names? I'm unfamiliar with Polish first names, so many of the Vaulter's heroes may be regular names in Poland. For instance a Vaulter's hero is named "Chief Sapper Liszt Ajandek", which may be a reference to Franz Liszt, the Hungarian musician. 

Several Forgotten heroes have the title "Sable", which could be a reference to an animal found in Russia (and used to be found in Poland): https://en.wikipedia.org/wiki/Sable . The Polish form of the name is soból , which is similar to the Russian version sobol. If you change the language of the game does Sable change too? 

It's plausible that the names are common IRL, such as "Nadjne" seeming to be a version of "Nadine". However perhaps the names simply sound plausibly Eastern European without holding any meaning themselves. 

I believe there are some Slavic inspirations in their names, but to get a definite answer we need to ask for an audience with our Narrative Emperor @Slowhands or with @StoryEngine .

The Mezari (United Empire in Endless Space) seem to often have Slavic-sounding names, and the Vaulters are their descendants, so I think it is likely. Yes.

Yes, I've always noticed they were Slavic. I thought from the descriptions they were a Kievan-Rus type mix of Scandinavian and Slav, but as I played them I couldn't actually see any Vikingness or Scandinavian names whatsoever, so those descriptions strike me as odd. Is there some aspect I'm missing?

Vaulters heroes have Hungarian names mostly. Some sound like Czech-Slovak. But I couldn't identify any Polish names.

Also, Kazanji is a Bulgarian surname and Yirmak is an archaic East-Slavic name, modern surname.

@StoryEngine and I wanted the UE and Vaulters to have generally Eastern European names; as my wife is half Hungarian and he lived in Budapest for a while they tend to be more Hungarian than Slavic (the roots of the two languages are radically different).

Just to differentiate, on several occasions we replaced an "i" in a name with a "j", as if the 'j' was a vowel. That's our fault, not the Slavs or Magyars :)

As far as additional Viking references go, the Vaulter ship types were generally based on equivalent Scandinavian or Viking ship names, from Old Norse if possible (knarr, karve, drekar, ...).

Finally, "kazanji" would translate literally from Japanese as "volcano people" ^^

-Slow