Those are interesting helmets: https://www.relicsww2.net/soviet-helmet-ssh-36-also-known-as-khalkhingolka/

Are we to assume, that this is a universe, where a Tsarist Russia used centaurs at Khalkhin-Gol?

sanitaeter said:

Those are interesting helmets: https://www.relicsww2.net/soviet-helmet-ssh-36-also-known-as-khalkhingolka/

Are we to assume, that this is a universe, where a Tsarist Russia used centaurs at Khalkhin-Gol?

Doesn't look that Russian to me.
Helmets look more like Stahlhelms with added metal (brass?) elements. Uniforms are definitely in German Heer spirit.
Not sure about rifles. Something between Finnish M39 Mosin rifle and Chinese Hanyang Type 88, maybe.

First, the helmets, the gray uniforms and the cut of the tunics look very Imperial German or Austrian to me, but that's just me speaking as an interested layman. The rifles? Not sure.

I would also note it makes sense for those girls to have their bayonets affixed even outside of combat. They would be more likely to use them like lances in combat situations, stabbing down at enemy soldiers from overhead.

Regarding the rifles, they look very similar to the German Gewehr 1888, although not 100% exact around the front barrel band/bayonet area.