If Ragunna's common echoes can't exist out of the Genesis Nexus range, how can the common echoes of Septimont do so, like the Wootahs ?

This just struck me today. Also, how do we figure out the "range" of a Genesis Nexus in question ? Like for the Ragunna city, I think it's only for within city limits right ? Could the other nexus have ranges that go beyond that ? Is that the reason why the common echoes in Septimont can exist out in the wilds, or common echoes in general can exist within Rinascita only because there's a Genesis Nexus around ?

Is that the reason why the echoes in that Echo village overlooked by Fulmine are able to maintain their forms because a Genesis Nexus with a larger range than the one in the Ragunna City fortunately happened to be by ?

Is there some story and lore reasons I'm forgetting ?