I think it's safe to say that there were no CoAs in TGS's timeframe at all. Not in Croatia and not anywhere else. Of course, that does in no way mean that we should leave the game's faction symbols blank (because the game *requires* a symbol for each faction). Actually, that's why we call it "faction symbol" and not a "CoA". Thus, I see absolutely no problem in using a decorational motiff from that time, especially one which later became a proper CoA - IIRC, similarly we use a lion for Bulgaria, as there are a number of Bulgarian lion decorations from the period and it later became a CoA of the state (when CoAs actually started appearing here).