It is doubtful that the Dilgari could have done so well if either the Narn or Centauri had been opposing them... Considering how big an impact EA had when entering the war to support the minor races, and at the time EA pretty much was a minor race, not nearly as big as Narns or the Centauri.
As I see it, EA entered the Dilgar war to show their newfound military power with their latest ships (Nova, Hyperion, Aurora) to other races. In my knowledge it was the first major conflict EA took part in, it was a necessary show of force to let other races to know that they won't be an easy target to any would-be-oppressor even if they're late in the game of space warfare.
You might want to ignore that as well Orpheus.
Most of the known facts about the Dilgar war were stated in the 9th episode of first season. No official TBP campaign with actual story should go directly against known facts that were stated in the show or movies, it would be simply twisted to do so.