Feel strange to me, why an Aedui Allied becomes subdue to Roman rule after being attacked by Arverni? Am I missing something?
If the Aedui are attacking Arverni or Belgic allied tribes, they're almost certainly being viewed by the locals as just another form of Auxilia.
That said, Roman-allied is a different tribal status entirely, marked with the red discs. It has some small benefit to the Romans, but they're typically just as happy with subdued for the most part.