As Kogg says: "You should explore some more too, I'm certain there's more places to reach!"
And Seevil : "You wouldn't believe the strange things I've seen lying around this place, shame there's too many monsters roaming about or I'd go hunting for more."
I don't get that text from Seevil even after clearing the entire island, including bosses. I do see an item that can be looted on top of a platform on island 2 I can't reach, but not sure what to do to get there. Kogg also has just stopped responding to hails, and Seevil just directs me to Kogg. All the bosses are dead, not sure if that makes a difference though.
So those quotes are from the characters after you create an expedition with the "svarock kill" flag. If you killed svarock then ran around the zone straight after withouth recreating it would still be the no-kill version of the zone. However, I'll make a note of that as might be able to change the current zone right after the svarock kill.