The war does not seem to have two clear-cut sides, but rather, several separate theaters of war.
I agree that it's split into several theaters but I disagree that you can't divide it into two sides. Just about every power has forged an alliance with Leopold or with the Astrocracies. Again it's not so different from WWI with the Allied and Central powers broken in to different theaters of war with their own prerogatives and agendas.
Must every war be the 'great' war? If BM keeps insisting on naming every war as 'great' then none can truly be judged as great. I can only count one 'great' war and that was the EC war that raged from 2004 to 2007, saw multiple realm deaths, the birth of new realms (some of which died along the way), repeated rebellions to switch sides, various intrigues, and was truly great.
Not to mention 'great' is such a bland adjective. Wars' names are best chosen in hindsight anyway, when the historians analyze them.
Yeah "great" is a little bland at least by itself it is. There doesn't need to be one name for the war, It's often the case that a name is chosen after the fact and in many cases wars never have one name. For example Japan considers World War II the final stage of "The Imperial Wars".
For the Astroist powers I'd suggest a few names all of which have heavy propaganda purposes of course:
The Final Crusade
The Holy War
The War for the Blood Stars
The War of (Heathen/Heretic/Apostate) Aggression
The War for the Faith of Dwilight
For more politically neutral terms:
The Pan Continental War