The Giant Toad Pond is halfway up Youkai Mt. according to
Perfect Memento in Strict Sense.
Now I moved it to 2 new locations. Location A and location B.

Location A. will require quite a lot of terraforming considering it would be on the slope of Youkai Mt. however that way would be more true to canon.
Location B. will be easier I assume. Since the ground is more flat in that area. It's not really half way up the mountain it's more near the base of it. Which in my opinion is fine.
Since Hina's house (15) has not been ported in I assume and the Youkai Forest is huge and empty I see no problem in pushing her house. to make room for the Giant Toad Pond