You have to meet Borky in each of the 9 different cities to tick each of the Knowledge points off for the Wanderer's Star.
The 10th one is done only when you have completed the 9 cities.
Borky seems to reset about 48 hours after the last time you completed Adonna Rioblanc's quest.
Once you have talked to Borky, he will disappear for several days. You won't be able to find him in any city. It about 4 days, then he will return and you can pick up the quest again. He will available again in all the posted locations.