As far as the Balkans being primarily non-European, the Greeks, Serbs, Croats, Albanians and others who live there would certainly dispute you on that!
The only way you can arrive at Europe having only 8 wars in the 19th century is if you count Southern and Eastern European countries as being not quite European!
It isn't widely remembered, but the Balkans were the "Near East" for most of this period. They were considered only marginally European at the time by "real" Europeans such as the French and British. A famous French saying of the time was that "Africa starts at the Pyrenees." Ahh, for the good old days of true non-PC-ness!
European countries, as you point out, fought a great many wars during the 19th century. Only a few of those were fought on the continent of Europe between nationalistic European states. The original author's contention was that Europe was in almost constant war during this period due to nationalism. I merely pointed out that this is hooey.