From a reddit thread about an interview held in Chokaigi.

Q: In a house at the Forgotten Springs, there is a memo floating in mid-air next to the miqo'te. Are you going to fix this?
Yoshi-P: Would it be better to fix it? Or would you rather be able to read what it says? laughs The Forgotten Springs actually went under heavy remodelling during development. At the time, there was a wall there in order to create a cultural sphere for the miqo'te tribe, but there was a decision made to remove it. I think that the person responsible removed the wall but forgot to remove the memo as well.