15pt. attribute quests question

There are 2 quests of this type in Prophecies and in Factions. I have a character that has done the first one in Tyria (Skyward Reach). Is it possible to do one of the ones in Cantha as well? Is the limit of these quests two or can I do both Cantha quests for an additional 30 points? Can anyone shed any light as to the limitations and requisites for these quests?

if your char is tyrian born, you cant do the canthan ones since all quests on shing jae are locked.

if you are a canthan born, i dont know, i think you can do the tyrian ones if you leave out the canthan ones, but you cant do more than 2 for extra attribute points.

I believe you can only do the ones from whichever continent you started with.