Another way to think about indicative vs. subjunctive usage with aunque

I read the lesson thoroughly, and Silvia’s answer below. I still struggled a bit with thinking about the mood of the sentence being determined by shared/non-shared knowledge or context in the case of a past event. For me, it has been a helpful trigger to think of aunque + indicative as directly translating to “even though”, but the situations that go to subjunctive something more like “while it may ”.  I think this fits with Silvia’s comment that the main point of the phrase is sort of what comes next, the background/shared information is an acknowledgement of context, not the primary statement. Think about our sample phrase: “Sí, pero aunque fuera un éxito, tuvimos que ceder demasiado por nuestra parte. “.  In my mind the approximate translation would be “Yes, while it may have been a success, we had to compromise too much on our side. And, “…might…” makes me think subjunctive. I hope this is accurate, and that it helps someone else.