Figured I'd give my interpretation of the artwork...
Looking at the first picture of the Honne Blog in the 'Unused Art' section, it reminded me of a couple different spots in the game...
Left: Mount Pyre... Possibly an unused entrance?
Middle: Part of the El Nido Traingle (Underwater) area, perhaps?
Right: Seems familiar, but I can't quite place a location... Closest I can think of would be Fossil Valley between Termina and Arni, though it doesn't match that style to well...
Looking at the second one, I came up with another idea... It's the right portion of the above drawing, though reflected, and finished. It reminds me of the Isle of the Damned that way... Perhaps it could have been the potential entrance from when you landed on the Isle itself?
The third one strikes me as another potential entrance to Mount Pyre... Actually, it's a finished drawing of the left portion from drawing one!
Moving onto the GamePro guide material...
Picture #1: Seems like something that could come from the Isle of the Damned... The floorwork is similar, if not as red... Also, the bones jutting everywhere are similar to other areas of the Isle.
Picture #2: Only one that really baffles me... I can't think of where this belongs, at all...
Picture #3: A picture of either Guldove or Arni, it seems... There is a boat similar to Korcha's under the right-side building, but the Fisherman in Arni had one, as well... But I think only Guldove had the red banners that come down from the main building...
Picture #4: Finished artwork for the middle section of the Honne Blog's first artwork. Strikes me as being underwater, based on the plants shown, though nothing else hints at it (There's a cloud in the background, after all...)
Bah, my ideas might be worthless... Thought I'd add my idea, though...