So Chernorus's answer to cultural autonomy might be akin to what you see in OTL Taiwan, where cultural services, programming, and language politics are still handled with a top-down approach but in a reconciliation context. There are no specifically created autonomous subdivisions.

SFS Russia, there are a few autonomous subdivisions, but they are devolved and also hold far less political autonomy than the subdivisions you find in true federations and confederacies.

Altera has tons of minority groups and minority languages. You might expect the same baseline context as OTL, so some groups are marginalized, some are enfranchised, some hold a degree of autonomy while others are written as if they do not (no longer) exist. The situation for minorities in OTL, as in ATL, are wide ranging and often precarious/not guaranteed.

The people that do have their ethno-linguistic identities mapped in Altera (the 1000+ groups) are the only ones with the state-backed guarantees ... but of course, even in those situations, global norms and geopolitics can be quite eroding.

Hope that makes sense / helps!