*As we have cliffs and obviously limestone(judging from the Baku) minerals will be easy to find to build roads and walk ways.
*Houses can not consist of limestone if they are to be underwater, neither can a Baku host a family subdue. I would suggest a rubber material both applied to houses subsurface and above it, Klesstron perhaps.
*Wave-inspired art, possibly air and earth influenced too.
Possible building materials
Klestron - Rubbery material used to cover buildings beneath and above surface.
Limestone[Bakla(Bak-la:Baku-stone)] - A very common mineral in Eklato Bay. Used for making pavement and complicated structures*once wet*
Deggu - Mangrove-like swamp tree. Used for furniture and structure skeletons because of rubber qualities when wet.
Personally, I think we should dig through what we already instead of making new materials which we forget along with the old materials. Keep old ideas alive. Klestron was a good and original idea, so was the high values of Limestone in Eklato Bay making it possible for the Baku to live.
I hope that helped some, i'm not sure it did.