True, the designations were all to do with geographic location along the line not ethnicity. During operation Bagration there were 3 Belorussian fronts 1st, 2nd and 3rd. Further back for example the divisions holding the northern part of the Don in the battle of Stalingrad were known as the Voronezh front. Named after a city. The designations were at times very confusing.

I don't think ethnicity played much of a role in how armies were assigned tasks or anything else, the thundering horde on the horizon had only one purpose.