I don't really have a lot of answers, but I am interested in this as well, specifically the Balkan Wars you mentioned. I always found it troubling to see the Serbs, Romanians, and Bulgarians fighting, but I guess our Western counterparts fought many bloody wars as well. I know there is a lot written down about relations between the Russian and Georgian Churches during the most recent war, but like you said, this is highly politicized, and some of the dialogue between the Churches seems to have been politicized as well.
I remember hearing a story that this question was asked by Japanese Orthodox Christians during the Russo-Japanese War, and they were instructed to pray for their country. I don't know if this is apocryphal or not, perhaps someone has a source for this?
Perhaps you could throw in some insights as to the opinions of Orthodox Poles concerning the numerous wars that were fought between Russia and Poland throughout the years?