I think they use a mutually intelligible language with local dialects.
EDIT:
Here's the wiki page on it:
"Say what you will of us, call us heathens because we deny your weak pretender-god. Call us savages because we strike at you, but know this -- it is we who are closest to the Ruinous Powers. We, most favoured of the gods, shall burn your lands, revel in your suffering, and destroy you. Despair...
warhammerfantasy.fandom.com
I don't know how accurate it is to canon though.
Well when in doubt, logic it out.
IRL steppe(and specifically steppe only) nomad tribes didn't really have a 'fixed' language canon. This is because of a number of major factors:
-Oral tradition.
-Extremely wide territories with very few people in them.
-Frequent osmosis from neighboring, more permanent cultures.
Words that don't get used, don't get kept.
What'd tend to happen as a result is that one tribe to another is usually fully mutually intelligible for a list of common subjects that both tribes encounter commonly, and then dissolve away into loanwords for rarer things.
To specify a recent example of the Wizard Wrangler, the discussion got sidetracked into Who was best suited for the position, if Panoramia was even competent, etc.
However, the original sentiment was to create a continuity for, what certain people believed at the time, an important job while we were gone. I don't think most people minded who got the job so long as Mathilde handled it before leaving, otherwise it felt irresponsible.
Yes, the thread quickly latched onto the idea of Panoramia being appointed, as you say she's somewhat popular, but it's really disingenuous to immediately tar any mentions of her to be under the motivation of Romance or relationships. Why the heck were people jumping straight into accusations of Nepotism back then?
If anything, it's the dislike of Panoramia that constantly gets "shoehorned" into any discussion involving her, which is very obvious with how controversial opinions are always thrown about, constantly emphasizing how she isn't special and shouldn't get perceived special treatment, when that wasn't even the point.
EDIT: a word 'Perceived.'
As far as I can tell the argument somehow mutated from "We should have a Wizard Wrangler appointed", which rapidly petered out as examples of how little actual authority is involved were highlighted.
To "Panoramia is an ideal Wizard Wrangler", which is a bit of a sudden leap when there's no actual justification for
having an official wrangler at all, but got a lot more engagement, because rather than a binary "yes, there's such a status" and "no, there's nothing to this other than being a contact person", it became a dispute about her personal merits and all the old stuff got dredged up for a second go.
To which I'd say that by dint of seniority, knowledge, prestige and personal power, Cython would of course be the objectively best choice as biggest kitty on the block.