Come to us, in times of leisure
Don't be blinded by the treasure - I haven't got the foggiest what this means. The only thing I can think of is that this tells us that it's a mini-game, and we should take the chance to play it instead of blasting through the story.
Maximising your potential
thrice from seven, quite sequential. - Do something four times? "Maximising your potential"...could be the Treno Monster battles, as there's 4 and they're usually a bit harder than you are.

Found by the nimrod that arrived
In home of minds which us contrived Nimrod = skilled hunter. The owner is a master hunter I think, I forget.
then headed linearly forth
four times, though still far from the north. Ack. [/intelligence and understanding]

So that's my guess. The Treno Monsters.