Does Belka/the Belkan Air Force have an official Emblem?
Actually they do:
(disregard black background, other images were massive pngs)
Same for Ustio, Yuktobania, Emmeria, Estovakia, Erusia, ISAF, Leasath and Aurelia (PSP game ones)
Note that roundel is different from emblem, ie:
Roundel (RAF):
Emblem (No 3 Squadron RAF):
As to why Project Aces decided to make everything with the same emblem, instead of having the chance of having a roundel, a number/letter and an emblem is beyond me, the plane has 3 slots, which normally are used to ID the aircraft squadron number(or letter if applies, for example prototypes and such), the squadron emblem and the roundel.
It could be done with one of the PSP games (Join Assault), as to why we can't in this game is hard to understand, I don't try to think about it too much but is a little off-setting if you want to have either IRL roundels or Strangereal ones, it might be because of how the story is set up but still doesn't explain why we can't mix them up since we could in older times.