I mean, that's the earliest point he could have known about us since our contact with Alexandria was nonexistent until then.
That said Calyx's interest in us seems to have been piqued by our defeat of Queen Eternal at the end of 7.0, if his comment during the Valia Pira fight ("I'm beginning to understand how you were able to defeat Queen Eternal.") is anything to go on. Our indomitability is clearly something he hasn't accounted for so far.