I'm pretty sure the only place he heard about "Enigmatic Gale" before the betrayal was that Pheonix Slayer mentioned it once in a really vague statement that might not make it's relevance to white haired guy clear. That pic from this episode is referring to how Evil Leader called white haired dude that when white haired dude had already betrayed them
Went back to that scene and it seems you're indeed right.
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Going back to Xam'd after 6 months with no recap might not have been the brightest idea as I have even less idea of what's going on then when I dropped it first time.