@Winchan Well, average translation contributed too, I guess. Plus, I don't 100% remember everything.
I was re-reading Ch1. After the defeat, the Empire "demanded wartime contributions from every other Kingdom". But Elvenide couldn't pay, so INSTEAD they summoned a Warrior. That they were supposed to send to the Empire.
...but they didn't. Did they eventually pay instead when Soma started making improvements? I forgot.
But in any event, my answers were based off my poor memory. Point is, the giving money was an "extra" (*stares at DEMANDING contributions*). It wasn't the Alliance per sé.
So, again. Why didn't Elvenide join the Alliance? I don't think it got explained.